From today’s New York Times, positive thinking isn’t all its cracked up to be:

More than two decades ago, I conducted a study in which I presented women enrolled in a weight-reduction program with several short, open-ended scenarios about future events — and asked them to imagine how they would fare in each one. Some of these scenarios asked the women to imagine that they had successfully completed the program; others asked them to imagine situations in which they were tempted to cheat on their diets. I then asked the women to rate how positive or negative their resulting thoughts and images were.

A year later, I checked in on these women. The results were striking: The more positively women had imagined themselves in these scenarios, the fewer pounds they had lost.