True vs self-righteousness

I have been pondering this since I heard it in my car early yesterday morning.

"I have said many times in years gone by that the only sin we can defeat is a forgiven sin. Let me say it more carefully this morning: the only sin that you can defeat in daily life and replace with righteousness is a sin forgiven for Christ's sake. I say it carefully because I know there are natural ways to overcome bad habits that aren't based on Christ at all. But when those changes occur in life without forgiveness from Christ, the result is not God's righteousness, but self-righteousness – which in God's eyes is no righteousness. So I say it again and carefully: the only sin that you can defeat in daily life and replace with righteousness is a sin forgiven for Christ's sake."

(Piper on Romans 8:1-4)