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.

The word consider suggests careful examination with a view to discerning and coming to some conclusion.

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 is found 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) and is translated: 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 is found 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.

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.

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.

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)

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’ (Ja 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)

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

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.

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 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 from sun = together + hiemi = send)  (Click here for word study on sunesis) is literally 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). See notes Colossians 1:9; Colossians 2:2. 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.

Note the "conditional promise" - Timothy is to consider (man's responsibility) and the Lord will give (God's part)

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)