This experiment comes from Madeleine Connolly. She writes for the BV Medium publication. This is taken from a piece she wrote where she describes suddenly realizing she's feeling better, and why. (Editor's Note: Anytime someone writes about something that works, I sit up and pay attention.)
I try to walk at least 20 minutes every day. Often it’s kind of incidental walking: walking home from work for 30 minutes instead of getting the bus, that kind of thing. That’s all I do.
I think it works.