The most secretive body parts are muscles, which hide behind layers of skin and appear only occasionally to help lift cars off trapped kittens. Flex your biceps in the absence of a cat emergency with today's Groupon to Butler Health & Fitness in Butler. Choose between the following options:

• For $49, you get a two-month gym membership (a $244 total value, including an $149 initiation fee).
• For $49, you get six weeks of boot camp (a $120 value)—plus before and after assessments (a $60 value), a nutrition plan (a $40 value) and a shopping guide (a $40 value; a $260 total value).
  
  

Butler Health & Fitness packs its expansive fitness facility with rows of workout machines and a slew of amenities that help exercise enthusiasts stay on track. The aerobic arena houses more than 100 pieces of Nautilus and plate-loaded equipment and more than 30 pieces of cardio equipment. Members practice butterfly strokes in the outdoor pool, stroke through racquetball bouts in the indoor courts, and join other fitness fans in more than 30 weekly classes, such as Zumba, Pilates, and Bodypump. An on-site sauna and spacious, shower-ready locker rooms round out the facility, giving athletes everything they need to push the limits of fitness and their ability to remember locker combos.

Muscle magnifiers can also boost their bodies with other boot campers under the encouragement of Butler's personal trainers, both of whom boast degrees in exercise science. The outdoor boot-camp program employs minimal equipment, focusing on the use of outside terrain, park benches, playgrounds, and unsuspecting pedestrians. The camp counselors conduct exercise and body-composition assessments of each participant before and after the camp to help measure body-shaping success. During the session, campers receive weekly educational emails, handouts, and rewards such as boot-camp T-shirts, water bottles, and bandanas.