Muscles are like stunt doubles—without proper training, they risk becoming nothing more than piles of goo. Cultivate sinewy fibers with today's Groupon: for $39, you get five mat Pilates or yoga classes at IM=X Pilates (a $100 value).

IM=X Pilates describes a fusion-fitness approach that blends the lengthening and muscle-toning action of Pilates with strength and cardio training for efficient body sculpting. Under the direction of experienced instructors, Pilates students use body bars and IM=Rings to perform core-strengthening techniques designed to tone muscles, sculpt leaner bodies, and perfect the art of breathing through the belly instead of the ears. Participants can also flex their bodies and unfold their consciousnesses during yoga classes, which focus on steady breathing tactics and slow, stress-taming movements. Improve balance, tackle tension, and increase endurance so effectively that muscles will be able to watch a six-part miniseries about dumbbells without complaining. Classes occur throughout the week and typically last an hour.