An interesting article here points to a study dune by Duke University Medical Center that treated depressed patients with a regimen of Zoloft, or exercise, or a combination of the both.

At the end of the four-month treatment period, all three groups exhibited similar results: significantly lower rates of depression.

What was interesting was that the depression relapse rate for patients who did only exercise was lower! The doctors theorized the following:

“It is conceivable that the concurrent use of medication may undermine the psychological benefits of exercise by prioritizing an alternative, less self-confirming attribution for one’s improved condition,”

Translation: realizing that you could get on a machine and kick depression’s ass on your own is empowering.

Beyond the physical benefits, its the feeling of empowerment and control that lead many to exercise.