A critique group member recently recommended this book, before working on her next WIP.
I like the idea of drilling down to figure out what really motivates your MC, and the fundamental tenet that your MC has to start the story with a misconception about him/ her self, or else s/he has no capacity for growth -- or at least, it's really hard to show that growth, if it's not centered around a misconception.
The best example of that, that I've read recently, is The Book of Boy. I won't spoil it by telling you what Boy's misconception is. This is one you've got to read for yourself! Absolutely excellent story.
As always, read and apply what you think will work for you and your writing. This is a good one to keep in mind, in reach on the shelf, and at-the-ready for your story planning phase (if you're a planner).