Take a stroll through the Hayes Valley neighborhood of San Francisco, and you might see something surprising: grown-ups on monkey bars. Most weekdays, scads of the city's chronically deskbound—stressed financiers, bleary-eyed techies—spend their midday break playing in the name of fitness. Their guiding light is Jennifer Pattee, who was once a desk jockey herself. While working as a graphic designer at Apple and IDEO, Pattee spent much of her time the way many of us do: sitting. (At a desk. On her couch. In her car.) She gained weight and battled anxiety. Many suffer worse fates: It's estimated that, worldwide, 5.3 million deaths a year are caused by physical inactivity (roughly the same number smoking causes). Fed up, Pattee quit her job and, in 2008, founded Basic Training
, an outdoor fitness company, to motivate a sedentary workforce with exercise that's fun. "Kids run, climb, jump rope," she says. "But they don't call it working out—they call it play." And they don't play on a treadmill, which is why Pattee's workouts take place in the streets and parks of San Francisco. She counts off pull-ups on low streetlights and tricep dips on the edge of a picnic table or leads jogs in neighborhoods chockablock with Victorians. (She also runs happy-hour classes that end at a local bar. We'll drink to that.) Last summer, with $55,000 in Indiegogo and corporate sponsor funding, Pattee and her partners turned a parking lot into a playground for adults. The worker bees swarmed, swinging from monkey bars and doing squats in the sunshine. "Exercise doesn't have to be 'no pain, no gain,'" Pattee says. "I want to come up with something so fun that people are inspired to get out there and do it."