Social support, peer pressure, family support -- all of that can be helpful, certainly in getting people to maintain exercise.

duration of exercise didn't seem to matter -- what seemed to matter most was whether people were exercising or not.

What the studies are showing is that exercise, at least when performed in a group setting, seems to be at least as effective as standard antidepressant medications in reducing symptoms in patients with major depression,

The important conclusion is that the effectiveness of exercise seems to persist over time, and that patients who respond well to exercise and maintain their exercise have a much smaller risk of relapsing,

They're in good shape, they exercise as a family ... they don't look like couch potatoes. They obviously make an effort to practice what they preach.

But we also know that these drugs aren't effective for everyone -- about a third of people aren't going to get better with medication.