It's something I've believed for a long time - anti-depressants aren't necessary when you can use exercise to achieve the same effects:

Exercise on par with drugs for aiding depression

by Stephanie Brail

While this article is intended primarily for people with chronic fatigue syndrome, it might also be helpful to anyone who is struggling with severe fatigue after exercise or physical exertion.

What often separates a person who has symptoms of fatigue, versus someone who has full-blown chronic fatigue syndrome, is the phenomenon known as “post-exercise malaise.” Post-exercise malaise (also known as post-exertional malaise) is one of the key symptoms of chronic fatigue syndrome that is used to diagnose the illness. It is characterized by severe fatigue and the worsening of other symptoms for the days following the exertion.

For most people with chronic fatigue syndrome, this translates into the following: When you try to exercise, you end up back in bed with your symptoms aggravated for a day, if not more. In some cases, too much exertion can cause a severe chronic fatigue flare-up or relapse.

Pat Gundry has started a "6 Month Fitness Project" to provide support for whatever your fitness goals happen to be. She has a blog with daily updates and a mailing list. As of this writing she is almost a week into it. To get your bearings, go here first:

http://www.6monthfitnessproject.com/about_the_project/index.html

The Feel Good Girl recommends the following six-part formula for creating a healthy, happy life:

Unplug.
Unplug from society's expectations of you. Unplug from the need for external validation. Unplug from messages that you need to be rail thin, younger, smarter, more beautiful, rich, and clothed in expensive designer-wear to be worthwhile.

Relax.
Relax not only means taking time out for some R&R, but also to relax about everything! Is the thing you are stressing out going to mean the end of the world and life as we know it? If not, learn to chill out about it.