Look at 1 Cor. 9:27 in your Bible.
I really liked this verse and 26 also in other versions.
1 Cor. 9:26 and 27
So I run straight to the goal with purpose in every step. I fight to win. I'm not just shadow-boxing or playing around.
Like an athlete I punish my body, treating it roughly, training it to do what it should, not what it wants to. Otherwise I fear that after enlisting others for the race, I myself might be declared unfit and ordered to stand aside
1 Cor. 9:26-27
Therefore I do not run uncertainly (without definite aim) I do not box like one beating the air and striking without an adversary.
But (like a boxer) I buffet my body (handle it roughly, discipline it by hardships) and subdue it, for fear that after proclaiming to others the Gospel and things pertaining to it. I myself should become unfit (not stand the test, be unapproved and rejected as a counterfeit.