"All things are lawful for me, but not all things are helpful. All things are lawful for me, but I will not be enslaved by anything." (1 Corinthians 6:12)
"We are saved by grace, not by our actions.
Therefore, Christians can technically do anything and retain their salvation, but God forbid that they would think that way (1Jo 3:3). Christians have a new nature that doesn't want to sin, and they are also aware that sin gives Satan access to them to cause misery and pain in this life.
This is the point that Paul was making. He was free in Christ to do whatever he wanted to do, but he didn't want to do anything that would bring him under the oppressive power of Satan. Those who have truly been born again get their "want to" changed.
Verse 13 is a continuation of the thought Paul had in the previous verse. Paul was free in Christ to do as he wished, but he chose not to do those things that gave Satan opportunity in his life." (Andrew Wommack)
