What does Paul mean when he says all things to all men? Can I be all things to all men? When it comes to sinful practices, no! Paul says even though I am free from all men I made myself a servant to all. This could be looked upon as kind of a riddle. How can he do that ? Why did he do that? So that the gospel of Christ can be real to all. So that people by Paul's life can be interested in what he had to tell them about Christ and Heaven. He had to deal with the Jews under the law of Moses, and the Gentiles without the law of Moses. If we are familiar with the book of Acts, then we know he did it very well.
Notice that to the weak he became as weak. Here it is not the sinful weak, but it means those who are not strong.
In verse 24 he compares the Christian life as running a race. He is not talking about competition but the prize. The runners had a perishable crown. A wreath that would soon wither away. Ours is imperishable in Heaven.
Paul was not an air boxer, just beating the air. His body was always in subjection to Paul, not Hims3elf in subjection to his body, always because oaf the souls of men and not for pleasurable enjoyment to the ruining of the body.