I love The Happiness Project. It sounds so cheesy, but this book (and the blog that predates it) have changed the way I think about so many things. It's not preachy and it's not some kind of self-help program -- just research on happiness, with some surprising results.

Somewhere along the line, I had come to think of myself as an essentially unhappy person. "I'm melancholic and critical by nature," I used to think, "I tend toward anxiety, brooding, and negativity. I can't change that, just learn to live with it as best I can."

Even though my own happiness project is a work in progress, I can't thank Gretchen Rubin enough for showing me that happiness is a behavior that can be learned.