Charles Ellicott Commentary 2 Timothy 2:5

"And if also a man contend in the games, he is not crowded, except he have contended lawfully." — 2 Timothy 2:5 (ASV)

And if a man also strive for masteries.—More accurately translated, again, if a man strive in the games. Another picture is drawn, and the picture is, as before, a well-known one to all the residents in the great cities of the empire. An athlete is chosen to represent the professed servant of Christ, one of those who, after long and careful training, contends in the public games, then so popular, so entirely a part of the life of every city—in the games of wrestling or running, or in the chariot-racing, or in the hand-to-hand contests. Again, this one—as in the case of the soldier—if he aspired to victory and success, must “endure hardness.”

Except he strive lawfully.—“Lawfully”—i.e. according to the prescribed conditions of the contest. He must, of course, submit to the strict rules of the arena where the games are held, and (for this is also included in “lawfully”) must also—if he hopes for a prize—go through all the long and severe training and discipline necessary before engaging in such a contest. Galen uses the same phrase, in the sense of complying with the recognised rules of training regarding diet.