You know what else Paul said?
That everything that is not of faith, is SIN. It's actually SIN, especially AFTER you've already been sanctified and bought and redeemed by Christ, to go back to trying to fix it yourself. HE begun a good work in you, and HE will complete that work. You began in faith, and you're supposed to continue in faith.
The problem is, you're not actually overcoming sin by this reliance on yourself. You can't do it, it will never happen. If it worked, we should see at least a few christians around who could honestly testify of the sins they've conquered. But we never hear that, not unless they're lying, or fooling themselves.
No, each and every time we hear a REAL, powerful, TRUE testimony, it's always about the power of GOD. Not our abilities.
Your attempts to resist sin will be as futile as the amount of effort you put into it. It is in and through and by CHRIST we RECEIVE victory, not by ourselves.
I have never freed myself of one single sin, and neither have you. Because you have never ever been able to do that. You, like the rest of us, needed a miracle, and we still need miracles every single day.
The struggle against sin is really the struggle against our own pride, because we always want to do God's work. But as Paul says, we can't boast of anything but our weakness. It's in our weakness that HE becomes strong.