When Dr. Alison Greenwood worked as a young teacher in a London high school 30 years ago, she ended up at her doctor’s office suffering from stress. She asked for antidepressants, but instead he advised something she wasn’t anticipating, which few GPs ever suggested back then.

“He told me: ‘Well, what you need to do is get outside,’” she recalls. He advised her to jog regularly along the Thames, and the benefits were transformative. “I’ve been doing that same five kilometer jog every week since,” she says.