THEREFORE: dio: (Click for the 5 therefore's in 1 Peter)

Spurgeon...

Therefore (1352) (dio) for this reason, for this purpose, because of this thing: What "thing" has Peter been taking about for 12 verses? Clearly "salvation"... one that even the prophets didn't fully understand (v10,11) & angels long to understand (v12) but cannot. And so with this therefore we see a change in emphasis. Peter has been dealing with the glories of our salvation. At this point, he launches into a series of exhortations based on the foregoing firm foundation.

Verse 13 serves as a hinge to connect 1:1–12 (assurance of future glory through new birth in Christ) with 1:14–5:11 (expectation of righteous behavior in spite of unfair circumstances).

Therefore or because you now have the foundational teaching about salvation, truths so magnificent that even angels long to look into, Peter says "turn that knowledge into 'shoe leather' and live it out before the lost world". The renewing of one's mind by these incredible truths should transform our walk (see notes Romans 12:2). In the  NT doctrine is always inseparably linked with practice. What you believe should manifest itself in how you behave. And in the later parts of this letter we see that Peter gets very specific about the behavior and actions that adorn the transformed life of a set apart one (a saint). Because you have been born again to a living hope, because you have an imperishable inheritance reserved for you in heaven, because you are protected by the power of God, because you can rejoice in suffering knowing it has a holy purpose in your life, etc...now do these things - gird your mind, keep sober and fix your hope. Note how Peter first gives instructions on grace before he asks them to live it out. Grace (God's transforming power that enables us to live a supernatural life) must be experienced before the behaviors called for can be put into practice. The alternative is to place yourself under legalistic constraints to do this or do that, and this self-effort approach cannot produce a supernatural life.

C H Spurgeon commenting on the importance of "therefore" in this section writes that

Doctrine may become dangerous if it be not reduced to practice, and all the doctrines of God’s Word may readily be turned to good and practical account if we are willing so to employ them. Those who regard doctrine simply as a subject for debate, an opportunity for displaying one’s argumentative powers, miss the mark altogether, for we are taught the truth in order that it may lead us to holiness of life. This is the object of God in giving us more light,— that, by that light, we may ourselves become more full of light, and be the means of conveying light to others. Therefore, when your mind is instructed concerning some grand truth, after you have sucked the honey and joy out of it, always say to yourself, “But what are the bearings of this doctrine upon my life? How should it influence me? What would God have me to do as the result of receiving such teaching as this?” From what Peter had already said, like a true logician, he draws a wise inference, and says, “Wherefore gird up the loins of your mind, be sober, and hope to the end for the grace that is to be brought unto you at the revelation of Jesus Christ." (Spurgeon, C H: Girded for the Work)

As an aside Peter is making it very clear that our faith (and the obedience that emanates from that faith) should be based not on our personal experiences but on the sound doctrine of the Word of God.

GIRD YOUR MINDS FOR ACTION: anazosamenoi (AMPMPN) tas osphuas (Loins = seat of strength of body) tes dianoias ~ what goes thru the mind = one's thought processes ~ generally "mind") humon:  (Ex 12:11; 1 Ki 18:46; 2 Ki 4:29; Job 38:3; 40:7; Isa 11:5; Jer 1:17; Lu 12:35; 17:8; Eph 6:14)

Therefore, prepare your minds for action (NIV)

Turn the robes of your mind into running shorts. Pull them up between your legs and tuck them into your belt (Piper)

So then, have your minds ready for action (TEV)

So brace up your minds (Amp)

be serious and thoughtful rather than shallow and flippant in attitude (Morris)

having tied up at the waist the clothes of your mind (ALT)

If you have never heard Dr Martyn Lloyd-Jones preach, click and sit quietly for 40+ minutes as he preaches a powerful message on "Trials and Temptations", filled with numerous practical insights on what it means to "Gird your mind for action". (Highly recommended)

Spurgeon comments that Peter

begins, as you notice, with girding up the loins of your mind. These are days of great looseness; everywhere I see great laxity of doctrinal belief, and gross carelessness in religious practice. Christian people are doing to-day what their forefathers would have loathed. Multitudes of professors are but very little different from worldlings. Men’s religion seems to hang loosely about them, as if it did not fit them: the wonder is that it does not drop off from them. Men are so little braced up as to conscientious conviction and vigorous resolve, that they easily go to pieces if assailed by error or temptation. The teaching necessary for to-day is this: “Gird up the loins of your mind,” brace yourselves up; pull yourselves together; be firm, compact, consistent, determined. Do not be like quicksilver, which keeps on dissolving and running into fractions; do not fritter away life upon trifles, but live to purpose, with undivided heart, and decided resolution." (Spurgeon, C H: A Seasonable Exhortation)

Gird your minds for action (328) (anazonnumi from ana = up ~stresses lifting up of long robe + zonnumi = bind about especially with a belt) is used only here.

Anazonnumi means to bind up, gird up, and was used literally that of a robed man, tucking his skirts under the belt, so he can be free to run (literally

Then the hand of the Lord was on Elijah, and he girded up his loins and outran Ahab to Jezreel." 1Ki 18:46;

Elisha

said to Gehazi, “Gird up your loins and take my staff in your hand, and go your way..." 2Ki 4:29,

Now Elisha the prophet called one of the sons of the prophets, and said to him, “Gird up your loins, and take this flask of oil in your hand, and go to Ramoth-gilead." 2Ki 9:1).

This was apparently a well known Hebrew expression indicating readiness of mind or preparedness. The Jews at Passover were supposed to eat the Passover meal in haste, "with (their) loins girded", ready to move

Now you shall eat it in this manner: with your loins girded, your sandals on your feet, and your staff in your hand; and you shall eat it in haste—it is the Lord’s Passover Ex 12:11

God commanded Jeremiah

Now, gird up your loins, and arise, and speak to them all which I commanded you. Do not be dismayed before them, lest I dismay you before them” (Jer 1:17).

Here the phrase is used metaphorically to suggest needful preparation for the fierce and intense conflict to come. This figurative use of girding of the loins presents the picture of courage or resolve that would be necessary, for the task he was called to do was not a pleasant one and would bring persecution. How did Jeremiah do? Jeremiah obeyed God's command and as a result became one of the most unpopular prophets in Jewish history! Measured by human standards, his ministry was a failure, but measured by the will of God, he was a great success. Jeremiah was called to difficult tasks to stand alone, to resist the crowd, and to be out of step with the world view and values of his day, a "girding of his mind" which Jeremiah maintained for over forty years!

God challenges Job to gird up his loins

Now gird up your loins like a man; I will ask you, and you instruct Me” (Job 38:3; cf 40:7)

This use is figurative referring to Job's mental outlook and not to his physical clothing. The point is that all of the uses constitute preparation necessary to makes a person ready to take action and move about freely without hindrance physically or figuratively. To fail to do so is to invite trouble.

Paul using a similar metaphor tells the Ephesian church to

Stand firm therefore, HAVING GIRDED YOUR LOINS WITH TRUTH" (see note Ephesians 6:14)

So the truth is what we are gird our minds with.  The Roman soldier. He would pull his tunic through his belt so his garment wouldn’t be in his way when he was in battle. Girding the loins was a mark of preparedness, and the soldier who was serious about fighting was sure to secure his tunic with his belt. Paul like Peter is telling us that we must be prepared and committed for spiritual battle.

A Jewish person preparing for to run, to fight or to apply themselves to any business requiring rapid motion, wouldn’t leave with his garments loose but would put on a belt and pull his garments through it. He was then ready to move. The same thing was true of a Roman soldier. He would pull his tunic through his belt so his garment wouldn’t be in his way when he was in battle. The apostle Peter is telling us that we must be prepared and committed for action.

The aorist tense pictures a past once-for-all completed action in preparation for a course of activity, a strenuous life of obedience. They were to have their minds in constant preparation to discharge the duties, or to endure the trials of life - like those who were prepared for labor, for a race, or for a conflict.

Middle voice indicates the action performed is for one's own benefit and conveys a reflexive sense - "Gird up for YOURSELF the loins of your mind”. The middle implies that the person does the girding in his own interest. The mind ought to be free from any hindrance (for example, fear or worry) to serve the Lord.

Jesus uses a similar figure in Luke to call His listeners to preparedness saying (KJV) "Let your loins be girded about"

NASB - Be dressed in readiness

NIV - Be ready for service (Lu 12:35)

Jesus like Peter is saying let all hindrances be removed out of the way and to be active, diligent, determined and ready to do business.

Peter calls us to the mental discipline of right thinking and one of the best passages to facilitate right thinking is to

let your mind dwell on" "whatever is true, whatever is honorable, whatever is right, whatever is pure, whatever is lovely, whatever is of good repute, if there is any excellence and if anything worthy of praise". (see note  Philippians 4:8)

Don't allow your thoughts to "roam about" and to harbor thoughts of lust or worldliness. Don't allow thoughts that corrode and corrupt our moral, godly fiber.

Pull your thoughts together! "Roll up your sleeves".

Obedience and a life of holiness is not produced from passivity but demands that we each individually make an active choice to cultivate the attitude and initiate right thinking (reading and meditating on the Word) and right actions that lead to holy living. This charge is similar to Paul's call to discipline ourselves for godliness (see notes 1Timothy 4:7; 4:8 cf notes 2 Peter 3:11; 12; 14; 2Cor 7:1 see notes Titus 2:11; 12;  13; 14). This is a call to bring all of one's rational and reflective powers under control by cutting off vague "loosely flowing" thoughts & speculations that lead nowhere and only hamper obedience. It is an essential preparatory action to the man who would live a life of holiness and successfully resist the dangers confronting the believer both then and now.

Gather your thoughts because "Loose thinking" will lead to "loose living". Mental slovenliness issues in moral disorder. (cp Pr 29:18). A disciplined mind is vital to a holy life.

One way to "gird your minds" is to take "every thought captive to the obedience of Christ" (2Cor 10:5 ). The believer is to grab hold of his mind and take charge of his thought life. Is my mind an open manhole into which anything can fall? Is it a drain that indiscriminately sucks in everything? An “open mind” can be a virtue—but a mind open to whatever a godless world has to dump into it is not a mind under the lordship of Christ.

In Martin Luther’s terms

You can’t keep the birds from flying over your head, but you can keep them from making a nest in your hair.

This is each believer's responsibility and if we don't carry it out we are in danger of becoming "dull of hearing" (see note Hebrews 5:11) and forgetting that "solid food is for the mature, who because of practice have their senses trained to discern good and evil." (see note Hebrews 5:14)

In order to "realize the full assurance of hope until the end" (see note Hebrews 6:11) we need to maintain "diligence" (eagerness, zeal) so "that (we) may not be sluggish, but imitators of those who through faith and patience inherit the promises." (see note Hebrews 6:12)

So girding up your mind involves removing anything that would hinder the free action of the mind in relationship to spiritual growth or progress.

The recipients of this letter are reminded by the apostle in 1 Peter 1:1 (note) that they are strangers, those who have temporarily settled down alongside of a pagan population and later as pilgrims (see note 1 Peter 2:11). As such they should always be ready to move. As the traveler, the racer, the warrior, and the laborer, gathered in their long and loose garments, that they might be ready in their business, so Christians should do in their minds and affections. The image is one of preparing for battle or rugged travel. The believer is to grab hold of his mind and take charge of his thought life—to bring it under obedience to Christ (2Cor 10:5). It is not physical exertion that Peter has in mind here, but mental. If the purpose of girding up the clothing was to put out of the way that which would impede the physical progress of an individual, the girding up of the loins of the mind would be the putting out of the mind all that would impede the free action of the mind in connection with the onward progress of the Christian experience, things such as worry, fear, jealousy, hate, unforgiveness, impurity. These things harbored in the mind prevent the Holy Spirit from using the mental faculties of the Christian in the most efficient manner, and impede growth in the "grace and knowledge of our Lord and Savior Jesus Christ." (see note 2 Peter 3:18)

Prior to entering his public ministry Jesus had been fully prepared by laying up the Scriptures as treasures in his heart. When tempted (Mt 4:1), Jesus relied upon the authority of God’s Word to ward off Satan’s attacks (Mt 4:4,). Your ability to withstand trials and temptations also depends upon how well you appropriate the Scriptures into your life. Have you, like Jesus, “girded your minds for action” (cf Josh 1:8, Ps 119:9, 11, Job 23:12)

The mind that is girded up and redirected by the Scriptures, will begin to think in a new way. However threatening the present, the fully girded-up mind will set its hope “perfectly” on God’s grace. The redirected mind will focus on God’s priority, holiness.

KEEP SOBER IN SPIRIT: nephontes (PAPMPN): (1 Peter 4:7; 5:8; Lu 21:34,35; Ro 13:13; 1Thes 5:6,7) (See Torrey's Topic "Sobriety") "be self-controlled" (NIV), "be sober (circumspect, morally alert)" (Amp)

The New Testament writers put heavy emphasis on using the mind as the principal avenue to Christian growth.

Keep sober in spirit (3525) (nepho) (Click study of nepho) literally meant free from drunkenness or the effects of intoxicants and figuratively as used by Peter means an evenness of mind especially under stress.

 The idea is to “make sure you keep all your faculties fully operational”. This trait describes one who is free from every form of mental and spiritual ‘drunkenness’, from excess, passion, rashness, confusion, etc. be well-balanced, self-controlled. Peter gives us an injunction to sane appraisal of the facts, without undue emotion and panic.

He says that we are to continually (present tense) make the choice of our will (active voice = volitional choice) to be watchful, calm and collected in spirit, temperate, dispassionate and circumspect in this present evil age. It's image of not being drunk when it comes to spiritual things and implies alertness and evaluating things correctly, because you see clearly, and your mind isn't numb with intoxicating influences. Such a person is able to see things without the distortion caused by worry, fear, and their related attitudes. He or she is well balanced and does not "get drunk" on the intoxicating "liquor" that the world so tantalizingly offers to the senses of our old flesh nature.

Calvin says that "be sober" refers

not merely moderation in eating and drinking, but spiritual sobriety rather, when we shut in all our senses, that they do not intoxicate themselves with the unlawful things of this world.

Why do we need to keep sober? Our old nature continually desires to rule and reign (see note Romans 6:12) and our adversary prowls around continually and "doth seek to work you woe" (see note 1 Peter 5:8). Without sobriety vigilance is impossible.

Sobriety includes the ideas of steadfastness, self-control, clarity of mind, and moral decisiveness. The sober Christian sets his priorities and not intoxicated by the allurements & snares of the world, like Internet, sporting events, movies, the passing pleasures of sin (see note Hebrews 11:25)!

Be sober, be watchful against all spiritual dangers and enemies, and be temperate in all behavior. Be sober-minded in opinion, as well as in practice, and humble in your judgment of yourselves. Be ready for the most strenuous mental endeavor. Never be content with a "flabby faith". It may be that you will have to discard some things and abstain from some others.

To be sober means to be filled with spiritual and moral earnestness, being neither overly excited on the one hand, nor indifferent on the other, but calm, steady, and sane (see note 1 Peter 4:7), doing one’s duty and fulfilling one’s ministry (see note 2 Timothy 4:5).

The sober person lives deeply. Their pleasures are not primarily those of the senses, like the pleasures of the drunkard for instance, but those of the soul. They are by no means a Stoic. On the contrary, with a full measure of joyful anticipation they look forward to the return of the Lord. But the sober individual does not run away from their task!

C H Spurgeon comments that

These are equally days in which it is necessary to say “be sober.” We are always having some new fad or another brought out to infatuate the unstable. Very good but very weak-minded people are apt to make marvellous discoveries, and to cry them up as if they had found the philosopher’s stone. In my short time I have heard, “Lo here!” and I have listened; and “Lo there!” and I have listened: the call has come from a third, fourth, fifth, sixth quarter in quick succession, and after all there was nothing worth a thought. The whole world had been going to be enlightened by some new light which Peter and Paul never saw, something far superior to anything known by any of the saints or sages of the church: but the grand illumination has not yet come off. “Be sober;” keep your feet; possess your souls; do not be carried away with every wind of doctrine; do not be little babies, to believe everything that is told you, whether it be a ghost story or a fairy tale.

Be sober: quit yourselves like men that have their wits about them. A very necessary word this in times when everybody seems excited; and some are so bewildered that they do not know their head from their heels. Crowds are prepared to follow any kind of foolery, whatever it may be, as long as it is advocated by clever men, and is made to tickle their fancy. Do but shout loudly enough, and many will answer: do but set open the door and beckon, and they will rush in, whatever the entertainment may be. Brethren, “be sober,” and judge for yourselves...

The second exhortation is — “Be sober” And does not that mean, first, moderation in all things? Do not be so excited with joy as to become childish. Do not grow intoxicated and delirious with worldly gain or honor. On the other hand, do not be too much depressed with passing troubles. There are some who are so far from sobriety that, if a little goes wrong with them, they are ready to cry, “Let me die.” No, no"... To be sober means to have a calm, clear head, to judge things after the rule of right, and not according to the rule of mob. Be not influenced by those who cry loudest in the street, or by those who beat the biggest drum. Judge for yourselves as men of understanding. Judge as in the sight of God with calm deliberation.

“Be sober,” that is, be clear-headed. The man who drinks, and thus destroys the sobriety of his body, is befogged, and muddled, and has lost his way. Ceasing to be sober, he makes a fool of himself. Do not commit this sin spiritually. Be specially clear-headed and calm as to the things of God. Ask that the grace of God may so rule in your heart that you may be peaceful and serene, and not troubled with idle fear on one side or with foolish hope on the other...

You know the word translated “be sober” sometimes means “be watchful;” and indeed there is a great kinship between the two things. Live with your eyes open; do not go about the world half asleep. Many Christians are asleep. Whole congregations are asleep. The minister snores theology, and the people in the pews nod in chorus. Much sacred work is done in a sleepy style. You can have a Sunday-school, and teachers and children can be asleep. You can have a tract-distributing society, with visitors going round to the doors all asleep; you can do everything in a dreamy way if so it pleases you. But says the apostle, — be watchful, be alive; brethren, look alive; be so awakened up by these grand arguments with which we have plied you already, that you shall brace yourselves up, and throw your whole strength into the service of your Lord and Master." (Spurgeon, C H: A Seasonable Exhortation)

Gill adds that being sober entails

not only intemperance in eating and drinking, which greatly