Love Yourself Like Your Life Depends On It - Kamal Ravikant

Essentially involves rewiring your brain by insisting to yourself that you love yourself. Got the author out of a depressed state where he hadn't left the house in months(?) even though it felt like bs when he first tried. Others have had similar success with it (note the high number of reviews).

Personally I appear to be naturally predisposed towards happiness; why I recommend the book is that it's the only thing I've heard of that seems to produce the same kinds of natural bursts of elation that I experience anyway.

The book is cheap and short, and the potential return is very high (if you're looking for stuff under the Happiness heading) so I would say that it's worth checking out.