For a small book, Peaks and Valleys packs a punch. In particular, it made me think about how much we really do create our own good and bad times, and how much our lives are a reflection of our attitudes.
Since reading this, I've been more aware of asking myself "what did I do to create this situation?" instead of going directly to "it's not my fault." And with that new awareness has come a sense of responsibility and empowerment, that I can make different choices to get different results.