There was a greater article from the Time Magazine website about the benefits of walking. Nothing new, or surprising, but still completely worth telling people about. Yes, walking will healthier, including: happier, and smarter. The article isn't very long and work the read. Check it out in the link below.
The Single Most Proven Way to Get Smarter and Happier
Coincidently, I was listening to something recently that said walking for 30 minutes, 5 times a week (or 60 minutes for 3 times a week), was 3 times more effective than Zoloft. MedlinePlus has a list of Zoloft (Sertraline) side effects that include hallucinating (seeing things or hearing voices that do not exist), and changes in sex drive or ability. I think I'd definitely choose walking.
I found supporting information on Exercise and Depression, at Harvard Health Publications, Harvard Medical School.