"Now we cannot discover our failure to keep God's law except by trying our very hardest (and then failing). Unless we really try, whatever we say there will always be at the back of our minds the idea that if we try harder next time we shall succeed in being completely good. Thus, in one sense, the road back to God is a road of moral effort, of trying harder and harder.
But in another sense it is not trying that is ever going to bring us home. All this trying leads up to the vital moment at which you turn to God and say,
'You must do this...I can't.'"

Mere Christianity (C.S. Lewis)