Mikala Jamison is the author of the Body Type newsletter.
I’d wager that many people subscribe to the Elle Woods school of how exercise alleviates depression: endorphins make you happy, happy people don’t shoot their husbands, etc. But endorphins are temporary—you’ve got to re-up them with every workout. That’s a harder sell than something like an antidepressant, which promises to permanently alter your brain chemistry as long as you take a pill every morning, no gym trip required.