WANT TO BE SMARTER AND HAPPIER? Exercise. I’ve had good luck with the Rippetoe approach, but it’s much more important that you do something vs. nothing, than that you do any particular kind of exercise. Even just getting off the couch more via a Fitbit is good. For the average American, there’s a lot of low-hanging fruit there.

UPDATE: Here’s a post on exercise from a while back. I’ve gone a bit harder-core on the Rippetoe stuff since then, but it’s basically the same.