1 Corinthians 9:24-27
9:24 Do you not know that in a race the runners all compete, but only one receives the prize? Run in such a way that you may win it. 

9:25 Athletes exercise self-control in all things; they do it to receive a perishable wreath, but we an imperishable one. 

9:26 So I do not run aimlessly, nor do I box as though beating the air; 

9:27 but I punish my body and enslave it, so that after proclaiming to others I myself should not be disqualified.