If my whole blog was populated by comments, articles and research on the affects of exercise on depression, I think that would be ok. I just came across this article today from Slate:
The author points out that not only is exercise (in this case, running) just as effective as medication for managing mild to moderate depression, but he also discusses why American physicians seem so reluctant to talk about it. One of my favorite stories involves just this issue where my client asked his psychiatrist about non-medication options for treating his depression. He reported that his psychiatrist had no idea what he was talking about. This is obviously a single case, but it's consistent with what's shared in this article.