The first great secret of holiness lies in the degree and the decisiveness of our repentance. If besetting sins persistently plague us, it is either because we have never truly repented, or because, having repented, we have not maintained our repentance. It is as if, having nailed our old nature to the cross, we keep wistfully returning to the scene of its execution. We begin to fondle it, to caress it, to long for its release, even to try to take it down again from the cross. We need to learn to leave it there. When some jealous, or proud, or malicious, or impure thought invades our mind we must kick it out at once. It is fatal to begin to examine it and consider whether we are going to give in to it or not. We have declared war on it; we are not going to resume negotiations. We have settled the issue for good; we are not going to re-open it. We have crucified the flesh; we are never going to draw the nails.
-John Stott, The Message of Galatians, p. 151-152