John Gill 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
In the Olympic games, by running, wrestling, leaping

yet is he not crowned ;
with a corruptible, fading crown, a crown made of herbs and leaves of trees, as parsley, laurel

except he strive lawfully ;
according to the laws and rules fixed for those exercises; so no man that calls himself a Christian, minister, or any other, can expect the crown of life, the prize of the high calling of God, except he runs the race set before him, in the right way; looking to Christ, the mark, pressing through all difficulties, towards the prize, and holds on and out unto the end.