1 Corinthians 9:26
I therefore so run, not as uncertainly; so fight I, not as one that beateth the air:
Note 14 at 1Co 9:26: Paul had reasoned in many ways with the Corinthians about deferring to the weaker believers in this matter of eating food that had been sacrificed to idols (see note 1 at 1Co 9:1). He here used sports and the receiving of a crown or prize to inspire them. He was saying that there will be a reward for those who deny themselves for the sake of others.
Many people deny themselves all kinds of luxuries so that they can win a trophy or award, yet few deny themselves so that they can receive a reward from the Lord. Eternal spiritual things are infinitely more important than temporary physical awards.
Note 15 at 1Co 9:26: Fritz Rienecker, in his "Linguistic Key to the Greek New Testament," translated this phrase this way: "I do not run as one who has no fixed and certain goal." Paul was very focused in his life, much more than any athlete who was only competing for a corruptible prize. Paul knew God's purpose for his life, and he had definite goals. He was running to win. He was looking for that knockout punch.