17 If I preach voluntarily, I have a reward; if not voluntarily, I am simply discharging the trust committed to me.
18 What then is my reward? Just this: that in preaching the gospel I may offer it free of charge, and so not make full use of my rights as a preacher of the gospel.
References for 1 Corinthians 9:18

Paul’s Use of His Freedom

19 Though I am free and belong to no one, I have made myself a slave to everyone, to win as many as possible.
References for 1 Corinthians 9:19
20 To the Jews I became like a Jew, to win the Jews. To those under the law I became like one under the law (though I myself am not under the law), so as to win those under the law.
References for 1 Corinthians 9:20
21 To those not having the law I became like one not having the law (though I am not free from God’s law but am under Christ’s law), so as to win those not having the law.
References for 1 Corinthians 9:21
22 To the weak I became weak, to win the weak. I have become all things to all people so that by all possible means I might save some.
References for 1 Corinthians 9:22
23 I do all this for the sake of the gospel, that I may share in its blessings.

The Need for Self-Discipline

24 Do you not know that in a race all the runners run, but only one gets the prize? Run in such a way as to get the prize.
25 Everyone who competes in the games goes into strict training. They do it to get a crown that will not last, but we do it to get a crown that will last forever.
26 Therefore I do not run like someone running aimlessly; I do not fight like a boxer beating the air.
References for 1 Corinthians 9:26
27 No, I strike a blow to my body and make it my slave so that after I have preached to others, I myself will not be disqualified for the prize.
References for 1 Corinthians 9:27