When I say I am defeated by some sin, I am unconsciously slipping out from under my responsibility. I am saying something outside of me has defeated me. But when I say I am disobedient, that places the responsibility for my sin squarely on me. We may, in fact, be defeated, but the reason we are defeated is because we have chose to disobey.
– Jerry Bridges, quoted in by Tim Chester in You Can Change (p. 120).