Stuart Smalley’s famous words of self love: "I'm good enough, I'm smart enough, and doggone it, people like me" could be hazardous to your mental health. A new study out of the University of Waterloo suggests that people with low-self esteem actually sink into a darker state of mind when they articulate self-affirmations. This is just the latest from a new batch of self-esteem studies. Joining us for a look at how the self-esteem movement has morphed since it burst onto the scene nearly 30 years ago is Takeaway science contributor Jonah Lehrer. Jonah is author of How We Decide and Proust Was a Neuroscientist.