Though fitness experts have tried to incorporate cherished childhood activities into workouts, Cardio Tiddlywinks and Pin the Tail on the Trainer have yet to achieve commercial success. Inject fun into your fitness regimen with today's Groupon: for $20, you get 24 day-passes to World Gym in Glendale (a $240 value).

World Gym's brick walls contain rows upon rows of pristine cardio and lifting machines across 18,000 square feet of floor space. Treadmills, ellipticals, and stationary bikes face flat-screen televisions and picture windows, invigorating cardiovascular pursuits with favorite programs and the innate evolutionary impulse to chase down passing cars. Assorted weight machines target and tone every muscle group, and free weights alight upon racks and benches. Daily attendees can crack open a schedule of group classes in such calorie-crusading disciplines as boxing, yoga, boot camp, and Zumba. Wearied clients retire to the clean locker rooms after their circuits, taking time to relax in the dry sauna, decompress in the private showers, or retrieve their belongings from the lockers that only open to the correct frequency of wet-towel whippings.