1 Corinthians 9:25

And every man that striveth for the mastery is temperate in all things. Now they do it to obtain a corruptible crown; but we an incorruptible (KJV)

Then: Paul has finally reached the point of his argument. Every man determined to follow Christ must also determine to be temperate, not self-indulgent. Self-discipline is a major requirement for any goal and that includes running a spiritual race to become like Christ. What's even better, the crown received is eternal. It doesn't sit on a shelf and gather dust (Wright, p. 120).

Now: Application then is exactly the same as application today. Everyone admires the winners, but do not notice the long hours of self-discipline required to train. If today's Christians want to be spiritual winners and attain that incorruptible crown, they need Paul's advice that self-disciplined, on-going training is necessary.