The Wieden & Kennedy gym is one sock-encrusted locker and a couple of medicine balls away from replicating the fourth-grade Phys. Ed. experience. That's okay with Dan Wieden. Back in 1982, when he and his partner, David Kennedy, were setting up their fledgling ad agency in Portland, Oregon, Wieden made sure that plans for their new offices included an authentic gymnasium - the kind with creaky wooden bleachers, a floating floor, wire-caged windows, and a time clock. He sought to create not just a perk or a playground, but a source of playfulness. The agency has played by jungle-gym rules ever since. And it has won by them: Its irreverent campaigns for such powerhouse clients as Nike, Microsoft, Coca-Cola, ESPN, and Miller Brewing Co. have made it one of the ad industry's most celebrated mavericks - while bringing in more than $500 million in annual revenues. The gym has become the "hearth" of creative production, says Wieden. The oversized half-court is the site of staff meetings, client presentations, and appearances by guest speakers like modern-dance pioneer Judith Jamison and movie director Gus Van Sant - and Wieden & Kennedy staffers shoot hoops there too. Locating physical and mental exercise in the same place has produced an important side effect: "We have more open, honest, and competitive discussions in the gym," says Wieden. Even more important than flexing muscles is creating an attitude. "The joy of having meetings in the gym is that you're immediately taken back to a less pretentious and less formal time in your life," he says. "You're able to look at things with a fresh eye."