1 Corinthians 9:19-27 (NASB)
19 For though I am free from all men, I have made myself a slave to all, so that I may win more. 20 To the Jews I became as a Jew, so that I might win Jews; to those who are under the Law, as under the Law though not being myself under the Law, so that I might win those who are under the Law; 21 to those who are without law, as without law, though not being without the law of God but under the law of Christ, so that I might win those who are without law. 22 To the weak I became weak, that I might win the weak; I have become all things to all men, so that I may by all means save some. 23 I do all things for the sake of the gospel, so that I may become a fellow partaker of it.
24 Do you not know that those who run in a race all run, but only one receives the prize? Run in such a way that you may win. 25 Everyone who competes in the games exercises self-control in all things. They then do it to receive a perishable wreath, but we an imperishable. 26 Therefore I run in such a way, as not without aim; I box in such a way, as not beating the air; 27 but I discipline my body and make it my slave, so that, after I have preached to others, I myself will not be disqualified.