I've been really enjoying Tim Chester's new book, You Can Change, soon to be published by Crossway. Here's one encouraging quote on God's work in sanctification:
I used to think sanctification was a bit like pushing a boulder up a hill. It was a hard, slow work and if you lost concentration you might find yourself back at the bottom. But it's more like a boulder rolling down a hill. There's something inevitable about it, because it's God's work and God always succeeds. The sad thing is that often I try to push the boulder back up the hill. I say, in effect: "Don't change me yet -- I like doing that sin." (p. 62)
Chester writes in an honest, fresh, and simple way about the gospel and how it changes us. I highly recommend it as a helpful resource for struggling Christians (that's all of us!) who need to be reminded of the hope we have in Christ.