Remember when the only gym you knew was of the jungle variety? It didn't feel like work, but all that climbing and hanging torched tons of calories while strengthening your muscles. Return to recess with this rut-busting plan designed by Amy Bento Ross, a trainer in Norwalk, CT. "You'll use a slide and a swing to do familiar toners, which engages more muscle groups than performing them on flat ground," Ross says. "Plus, hefting your weight on the monkey bars and a bridge targets every inch of your upper body without dumbbells." Crank out these moves midway through a park run or do them in place of a regular sculpting session -- and put the fun back in your fitness routine.