Note: this is very tentative. I wonder if the well know threefold metaphor- soldier, athlete, farmer – is paralleled by three statements from the apostle about his suffering/endurance/sacrifice in the gospel. The section begins and end with reference to passing the truth on to faithful teachers.
A. 1 Thou therefore, my son, be strong in the grace that is in Christ Jesus. 2 And the things that thou hast heard of me among many witnesses, the same commit thou to faithful men, who shall be able to teach others also.
B. 3 Thou therefore endure hardness (kakopatheo), as a good soldier of Jesus Christ. 4 No man that warreth entangleth himself with the affairs of this life; that he may please him who hath chosen him to be a soldier.
C. 5 And if a man also strive for masteries, yet is he not crowned, except he strive lawfully.
D.6 The husbandman that laboureth must be first partaker of the fruits.
E. 7 Consider what I say; and the Lord give thee understanding in all things.
B’. 8 Remember that Jesus Christ of the seed of David was raised from the dead according to my gospel:9 Wherein I suffer trouble (kakopatheo) , as an evil doer, even unto bonds; but the word of God is not bound.
C’. 10 Therefore I endure all things for the elect’s sakes, that they may also obtain the salvation which is in Christ Jesus with eternal glory.
D’. 11 It is a faithful saying: For if we be dead with him, we shall also live with him:12 If we suffer, we shall also reign with him:if we deny him, he also will deny us:13 If we believe not, yet he abideth faithful:he cannot deny himself.
A’. 14 Of these things put them in remembrance, charging them before the Lord that they strive not about words to no profit, but to the subverting of the hearers.