Don't let the lack of heavy metal fool you. These equipment-free firmers sculpt killer curves. "Using gravity and your body weight as resistance can be just as effective as what you can do with any dumbbell, machine, or barbell," says workout designer Tom Vincent, a trainer at Juliet Kaska's Zen Fitness in West Hollywood who routinely puts his clients through their paces in the park. "You use multiple muscles in these moves, meaning a larger calorie burn in less time." Stick with this workout or pair it with pool sessions, taking a day off in between to allow muscles to recover. Do two sets of each move, leaving little rest between sets to boost your fat burn.