Flow caught my eye between the mental disorders and sexual insights of the psychology book shelf. I'm 7 chapters in, so I'm not here to give a review of this book. But I would love to introduce you to the author, Mihaly Csikszentmihalyi (pronounced / MEE-hy CHEEK-sent-mə-HY-ee). A wonderful writer who strongly illustrates the notion of living in a flow state. That is to say, a state of true happiness.
I'm very much against the state of the "self-help" industry, and wouldn't classify this as a "self-help" book by any stretch. Rather, it's a compelling look at what FLOW is, and it's causations. The video below was filmed at TED, and I think it's a nice introduction to his work. Maybe, just maybe, you'll pick it up. If you do, bring a highlighter.