The Alchemist by Paulo Coelho. I had to read it back in high as part of my AP Lit course. It's not a very long book but it is very well written and teaches you to enjoy life and live out your dreams.
I got the impression from reviews on Amazon that it might have to do with "the law of attraction" (which I dislike), because a lesson in the book is about the universe conspiring to help you when you want something badly enough. Is "the law of attraction" a major theme?