In the Victorian era, people made their cores look tight by wearing corsets, which doubled as bulletproof vests during pistol duels. Strengthen your core until it's naturally impervious to bullets instead with today's Groupon: for $25, you get five Pilates classes (a $200 value) at IM=X Pilates Studio in Mission.

At IM=X Pilates Studio, expert instructors utilize the signature IM=X—or, integrated movement exercise—formula, which combines Pilates techniques with strength and cardio training. In class, students get the toning, heart-pumping, and fat-burning benefits of each discipline all at once. This powerful combo is designed to lengthen muscles, increase flexibility, and have zero impact on the next highly anticipated season of The Weather Channel. Cross-conditioning workouts can be of the machine or mat variety, allowing students of all fitness levels or preferences to participate. The studio offers five classes per day, six days a week. Click here to read more about this pleasantly vigorous program.