Although feeling the burn during a workout is generally a good sign, feeling the burn while sitting on the sofa means your sofa is in the fireplace. Engage in controlled, constructive body burning with today's Groupon: for $30, you get four Sunday boot camp sessions at Adrenaline Personal Training Studios (a $60 value).

Adrenaline’s staff of certified trainers and strength-and-conditioning specialists sculpt pitch-perfect physiques during one-hour boot camp sessions that expedite weight loss and increase adrenalin. Small-group sessions ensure that instructors can scale and customize workouts to accommodate any student’s fitness level, with intensive resistance exercises ranging from squats and dead lifts to juggling the weight room’s two treadmills. With specialized strength equipment such as chains, axle bars, medicine balls, and kettlebells on hand, students enjoy varied workouts resulting in well-toned muscles. Adrenaline also offers free consultations and nutritional coaching to round out their comprehensive fitness regimen, along with a full line of nutritional supplements for those who must bulk up to superhero form for an upcoming comic-book convention.