Be grasping the meaning of that which I am saying (Wuest)

Reflect on what I am saying (NIV)

Think over these three illustrations (TLB)

Think over these things I am saying [understand them and grasp their application] (Amp)

Consider (3539) (noeo from nous = mind, the seat of moral reflection) has the basic meaning of direct one's mind to something and thus means more than just take a glance at. It means to perceive with the mind, to apprehend, to ponder (= weigh in one's mind, think especially quietly, soberly and deeply). It means to consider well, to reflect on with insight, or to think over a matter carefully. The idea is to grasp or comprehend something on the basis of careful thought.

Consider means to fix one's mind upon, to think about carefully, to give careful examination with a view to discerning and arriving at a judgment or conclusion. The idea is to ponder or  examine attentively or deliberately.

The NIV translates it reflect which suggests unhurried consideration of something recalled to the mind, and gives one the picture of meditating on these truths. Note well the order -- We are to do our part and can be assured the Lord will do His part (last part of this verse) and give you insight.

Moulton and Milligan...

The phrase "noon [noeo] and phronon" (Ed: loosely translated "I am keeping watch over my mind") is common in wills of both the Ptolemaic and the Roman periods...the testator thus certifying himself as “being sane and in his right mind”.

Noieo is present tense (calling for continuous action, make it your lifestyle), active voice (subject carries out the action by choice of their will) and imperative mood which indicates this is a command and merely advice or a suggestion! It is imperative that Timothy keep considering carefully, pondering and mulling over all that Paul had just said. By way of application, it is imperative that all believers seriously consider what Paul has written in verses 1-6 - We need to make this our continual practice or our lifestyle. Continually considering God's truth is another way of describing meditating on God's Word, a practice that always bears fruit...

This book of the law shall not depart from your mouth, but you shall meditate on it day and night, so that you may be careful to do according to all that is written in it; for then you will make your way prosperous, and then you will have success. (Joshua 1:8-note)

Psalm 1:1 How blessed is the man who does not walk in the counsel of the wicked, Nor stand in the path of sinners, Nor sit in the seat of scoffers! 2 But his delight is in the law of the LORD, and in His law he meditates day and night. 3 And he will be like a tree firmly planted by streams of water, Which yields its fruit in its season, And its leaf does not wither; And in whatever he does, he prospers. (See notes Psalm 1:1;  1:2; 1:3)

Wuest writes that noeo...

means “to perceive with the reflective intelligence.” It is distinguished from the mere physical act of seeing. It is the perception of the mind consequent upon seeing. In the New Testament it is never used of mere physical sight. (Wuest, K. S. Wuest's Word Studies from the Greek New Testament: Studies in the Vocabulary of the Greek New Testament: Grand Rapids: Eerdmans)

Vincent adds that...

signifies to perceive with the nous or reflective intelligence. In Classical Greek of seeing with the eyes, sometimes with ophthalmois expressed; but as early as Homer it is distinguished from the mere physical act of vision, as perception of the mind consequent upon seeing. Thus the phrase "and seeing him he perceived" (Il. xi. 599). In NT never of the mere physical act. Here is meant the inward perception and apprehension of the visible (Ed note: i.e., what transpires in the mind after one sees what he sees). (Greek Word Studies)

Vine writes that

the verb noeo means to exercise the mind by way of discernment, enabling us to enter into the circumstances of what is mentioned. (Vine, W. Collected writings of W. E. Vine. Nashville: Thomas Nelson )

TDNT writes that noeo means...

“to direct one's mind to.” At first it is used in the broad sense “to perceive,” but later it means only “to perceive mentally” and then “to think,” “to understand,” “to intend,” and “to know” as a function of the mind (nous). In the LXX the organ of noein is often the heart (kardia), but the sphere of noein is always mental. In the NT the verb has such senses as “to note,” “to grasp,” “to recognize,” “to understand,” and “to imagine.” (Kittel, G., Friedrich, G., & Bromiley, G. W.  Theological Dictionary of the New Testament. Eerdmans)

Paul is commanding Timothy to not just look at what he had written but perceive (derived from Latin percipere = seize entirely in turn from per- = thoroughly + capere = to grasp) what I have said by reflecting on it and giving it consideration so that you will gain insight. Since several thought had been compressed into three metaphors without any lengthy exposition furnished Timothy is told to put his mind on that which Paul has just said. Reading it is not enough! Ponder it. Chew on it. Digest it. And be assured that when you do, the Lord Himself will make this mental activity fruitful ("will give you understanding").

Noeo - 14 times in the NT - Matt 15:17; 16:9, 11; 24:15; Mark 7:18; 8:17; 13:14; John 12:40; Rom 1:20; Eph 3:4, 20; 1 Tim 1:7; 2 Tim 2:7; Heb 11:3. N             AS translates: consider, 1; perceive, 1; see, 1; think, 1; understand, 9; understood, 1.

Matthew 15:17 "Do you not understand that everything that goes into the mouth passes into the stomach, and is eliminated?

Matthew 16:9 "Do you not yet understand or remember the five loaves of the five thousand, and how many baskets you took up?

Matthew 16:11 "How is it that you do not understand that I did not speak to you concerning bread? But beware of the leaven of the Pharisees and Sadducees."

Matthew 24:15 "Therefore when you see the abomination of desolation which was spoken of through Daniel the prophet, standing in the holy place (let the reader understand),

Mark 7:18 And He said to them, "Are you so lacking in understanding also? Do you not understand that whatever goes into the man from outside cannot defile him;

Mark 8:17 And Jesus, aware of this, said to them, "Why do you discuss the fact that you have no bread? Do you not yet see or understand? Do you have a hardened heart?

Mark 13:14 "But when you see the abomination of desolation standing where it should not be (let the reader understand), then let those who are in Judea flee to the mountains.

John 12:40 "He has blinded their eyes, and He hardened their heart; lest they see with their eyes, and perceive with their heart, and be converted, and I heal them."

Romans 1:20 (note) For since the creation of the world His invisible attributes, His eternal power and divine nature, have been clearly seen, being understood through what has been made, so that they are without excuse.

Ephesians 3:4 (note) And by referring to this, when you read you can understand my insight into the mystery of Christ,

Ephesians 3:20 (note) Now to Him who is able to do exceeding abundantly beyond all that we ask or think, according to the power that works within us, (Comment: In this use the idea is to form an idea about something, think, imagine)

1 Timothy 1:7 wanting to be teachers of the Law, even though they do not understand either what they are saying or the matters about which they make confident assertions.

2 Timothy 2:7 (note) Consider what I say, for the Lord will give you understanding in everything.

Hebrews 11:3 (note) By faith we understand that the worlds were prepared by the word of God, so that what is seen was not made out of things which are visible.

Noeo - 31 times in the Septuagint, LXX, (1Sa 4:20; 2 Sam 12:19; 20:15; Job 33:3, 23; Pr 1:2-3, 6; 8:5; 16:23; 19:25; 20:24; 23:1; 28:5; 29:19; 30:18; Isa 32:6; 44:18; 47:7; Jer 2:10; 10:21; 20:11; 23:20). Note the concentration of uses in Proverbs.

It is interesting that the first three NT uses of noieo were by Jesus questioning His disciples ability to understand what He was saying. For example He said

"How is it that you do not understand (noieo) that I did not speak to you concerning bread? But beware of the leaven of the Pharisees and Sadducees. Then they understood (suniemi = put the pieces together as used in last part of this verse) that He did not say to beware of the leaven of bread, but of the teaching of the Pharisees and Sadducees." (Mt 16:11, 12)

Jesus' rhetorical questions were meant to rebuke the disciples for not perceiving the true significance of the miracle. But beloved, are we not so often like them, slow to understand the things of the supernatural Word, the things unseen, the things eternal (2Cor 4:18-note)!

D A Carson makes an excellent point regarding the relationship between understanding spiritual truths and faith writing that "The miracles Jesus performs, unlike the signs the Pharisees demand, do not compel faith; but those with faith will perceive their significance.”

So just as Jesus used "leaven of bread" to illustrate the effects of the "teaching" of the Pharisees, so too Paul used three well known professions to give Timothy insight into how he should fight the good fight.

Barnes commenting on consider says that

The sense is “Think of the condition of the soldier, and the principles on which he is enlisted; think of the aspirant for the crown in the Grecian games; think of the farmer, patiently toiling in the prospect of the distant harvest; and then go to your work with a similar spirit.” These things are worth attention." As the Lord gives you insight and helps you understand the illustrations, apply them to your ministry situation.

Say (lego) is in the present tense meaning “what I am saying”. In context Paul is referring to the six previous verses, particularly the three illustrations that have been given.

Wuest quotes Expositor's...

‘Grasp the meaning’ of these three similes...If you have not sufficient wisdom to follow my argument, ‘ask of God who giveth to all men liberally’ (Jas 1:15).” Paul had used the illustration of a soldier. Timothy was to live a rugged, strenuous Christian life in which hardships as the result of serving the Lord Jesus were an expected thing. He used the simile of a Greek athlete. Timothy should live a life of rigid separation, not merely with respect to evil things, but also with regard to things which, good in themselves, would unfit him for the highest type of Christian service. Paul now uses the metaphor of a tiller of the soil. Timothy is reminded that the Christian worker who labors with wearisome effort in the Lord’s service, has the right to derive his financial support from it, so that he might be able to give all of his time and strength to his work. (Wuest, K. S. Wuest's Word Studies from the Greek New Testament: Studies in the Vocabulary of the Greek New Testament: Grand Rapids: Eerdmans)

John Piper has a chapter entitled "Brothers, Let us Query the Text" which relates to seriously, intentionally, diligently considering what God's Word says

IF THE BIBLE is coherent, then understanding the Bible means grasping how things fit together. Becoming a Biblical theologian, which every pastor should be, means seeing more and more pieces fit together into a glorious mosaic of the divine design (Ed: As an interesting aside, putting together the pieces is the essence of the meaning of the Greek word for understanding = sunesis). And doing exegesis (Ed: derived from Greek word meaning "to guide", "to bring out" or "to lead out" and so means to arrive at an explanation or critical analysis and interpretation of a Biblical text) means querying the text about how its many propositions cohere in the author’s mind, and through that, in God’s mind. If we are going to feed our people (Ed: cp Jesus' charge Jn 21:15KJV Jn 21:16KJV Jn21:17KJV), we must ever advance in our grasp of Biblical truth. We must be like Jonathan Edwards who resolved in his college days, and kept the resolution all his life,

Resolved: To study the Scriptures so steadily, constantly, and frequently, as that I may find, and plainly perceive, myself to grow in the knowledge of the same.

 Growing, advancing, increasing—that is the goal. And to advance we must be troubled by Biblical affirmations....

“People only truly think when they are confronted with a problem,” said John Dewey. “Without some kind of dilemma to stimulate thought, behavior becomes habitual rather than thoughtful.”

He was right. And that is why we will never think hard about Biblical truth until we are troubled by our faltering efforts to grasp its complexity. We must form the habit of being systematically disturbed by things that at first glance don’t make sense. Or to put it a different way, we must relentlessly query the text. One of the greatest honors I received while teaching Biblical studies at Bethel College in St. Paul, Minnesota, was when the teaching assistants in the Bible department gave me a T-shirt which had the initials of Jonathan Edwards on the front and on the back the words: “Asking questions is the key to understanding.”

FOR THE LORD WILL GIVE YOU UNDERSTANDING IN EVERYTHING: dosei (3SFAI) gar soi ho kurios sunesin en pasin: (Ge 41:38; 39 Ex 36:1; 2 Nu 27:16;17 1Ch 22:12; 29:19; 2Ch 1:8, 9, 10, 11, 12; Ps 119:73;125,144,143:8,9; Pr 2:3, 4; 2:5,6 Is 28:26; Da 1:17; Lk 21:15; 24:45; Jn 14:26; 16:13; Acts 7:10; 1Cor 12:8; Eph 1:17; 18 Col 1:9; Jas 1:5; 3:15; 3:17 1Jn 5:20)

Other translations - the Lord will give you insight into all this (NIV), and may the Lord help you to understand how they apply to you (TLB), Think over these things I am saying [understand them and grasp their application], for the Lord will grant you full insight and understanding in everything (Amp), Put your mind on what I say, for the Lord will give you understanding in all matters.

For - This is a term of explanation and explains why we should make it our habitual practice to consider what God says in His Word. We are to be motivated by His promise to give us understanding.

For the Lord will give you understanding (cp Lk 24:45, Ps 119:130-note) - Observe that this divine promise of understanding is based on the condition that one ponders (in contrast to "speed reading" the Word -- you are not doing yourself any "favors" by reading through the Bible in a year unless you are making time to humbly let that rich Word course through and transform you! Ro 12:2-note, Eph 4:23-note) the truths in 2Ti 2:2, 3, 4, 5, 6. And remember that 2Ti 2:1-note explains how (continually strengthened [being enabled] by the transforming grace in Christ Jesus, made manifest and effective now by His Spirit Who indwells every believer forever!) one can even be enabled to function as a God glorifying, Christ exalting, Spirit led teacher, soldier, athlete or farmer (all metaphorically speaking except for "teacher").

In other words, Paul is stating a "conditional promise" - Timothy is to consider (man's responsibility, albeit even this is enabled by the Spirit - see Phil 2:13-note where He gives us the "desire" or "want to"!) and the Lord will graciously give us understanding (God's part). This truth flies in the face of the common false teaching of "let go and let God".

In other words, even Christ followers would not be able to understand the supernatural Word without the Spirit's supernatural enablement, His dunamis, His enabling power! The Spirit of Truth (Jn 14:17, 15:26, 16:13) takes the Word of Truth (2Ti 2:15-note; James 1:18-note, 2Cor 6:7, Ps 119:43-note, Col 1:5-note where "Word of Truth" is synonymous with "The Gospel"! We are not just saved in the past by the Gospel, but are saved/sanctified daily by that same Gospel and in the same manner, by faith, renouncing self-effort, self-reliance and resting/relying on God's Word and His Spirit to enable us to obey that Word) and daily (if we go to His Word daily [Mt 4:4, Lk 4:4] - you do don't you?) opens our "minds to understand (suniemi) the Scriptures" just as Jesus did for His first disciples (Lk 24:45)..

but just as it is written, "THINGS WHICH EYE HAS NOT SEEN AND EAR HAS NOT HEARD, AND which HAVE NOT ENTERED THE HEART OF MAN, ALL THAT GOD HAS PREPARED FOR THOSE WHO LOVE HIM." (Ed: Yes, this could be applied to our glorious future, our Blessed Hope, but it also applies to our blessed now...) For to us God revealed (apokalupto = the Holy Spirit "takes the lid" off of the supernatural Word so that we might see the Truth therein! Hallelujah!) them through the Spirit; for the Spirit searches all things, even the depths of God. Now we have received, not the spirit of the world, but the Spirit Who is from God, that we might know the things freely given to us by God (Ed: Especially His Word of grace" Acts 20:32), which things we also speak, not in words taught by human wisdom, but in those taught by the Spirit, combining spiritual thoughts with spiritual words. (1Cor 2:9-13).

MacDonald comments that

But there is more in these three illustrations of Christian service than appears on the surface. Timothy is exhorted to consider them and to meditate on them. As he does so, Paul prays (Ed: MacDonald's interpretation is based on the KJV rendering but most modern version see it as result of Timothy pondering rather than of Paul praying) that the Lord will give him understanding in all things. He will realize that the Christian ministry resembles warfare, athletics, and farming. Each of these occupations has its own responsibilities, and each brings its own reward. (MacDonald, W., & Farstad, A. Believer's Bible Commentary: Old and New Testaments. Nashville: Thomas Nelson)

Understanding (4907) (sunesis [word study] from sun = together + hiemi = send)  literally describes a sending together as of two rivers converging into union as one tributary. As an intellectual faculty sunesis describes the putting together of the pieces so to speak so that there is comprehension and perception. It is the ability to understand facts and concepts, especially to see the mutual relationships between the various "parts" to the "whole".

A T Robertson comments on understanding writing that it means...

“Comprehension” (from suniemi = to send together, to grasp). Col 1:9-note; Col 2:2-note. This is a blessed promise that calls for application. (2 Timothy 2)

Sunesis also describes the ability to assess any situation and decide what practical course of action is necessary within it. If Timothy would reflect on Paul's teachings in the previous verses, Christ would assemble the truths together for him and deepen the meaning.

D Edmond Hiebert comments that...

It is not that Timothy cannot grasp the meaning of the figures, but there is so much involved in them that he must be applying his mind to them to apprehend their full application. And Timothy need not fear that the mental activity demanded will be ineffectual. He is given the assurance that "the Lord shall give thee understanding in all things." (The reading in the King James Version, making it a prayer, is based on a reading less well attested.) He need not depend upon his own imperfect, erring mental faculties; for the needed enlightenment he is directed to the Lord.

Timothy was referred for insight and exposition not to the Church, not to the Apostle, or to the Apostles, but to the divine Master Himself, present, attentive, cognizant of Timothy's individual difficulties and mental needs (Moule).

The apprehension of spiritual truth is not primarily a matter of mental acumen but of spiritual teachableness. (2 Timothy by D. Edmond Hiebert).

MacArthur applies Paul's command to all believers...

Think over and carefully ponder what Paul has said. Look at your life and ask yourself if you are a faithful, trustworthy, spiritually mature believer? Are you devoting yourself to guarding and teaching God’s Word? Do you deny yourself and count your life as nothing in order to faithfully serve the Lord? Do you put some distance between yourself and the routine business of the world? Do you continually prepare yourself to serve your Master? Do you understand self-denial and self-sacrifice? Are you willing to pay the price that He demands?” “If you can answer yes to those questions,” we are promised, the Lord will give you understanding in everything. You will be led with wisdom and insight through the challenges to victory. (MacArthur, J. 2 Timothy. Chicago: Moody Press)