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 with today's Groupon: for $29, you get one month of unlimited Pilates mat and group fitness classes at Inline Private Training (up to a $100 value). The Groupon also includes 25% off a 60-minute wellness massage.

From his beauteous, plant-festooned base in the Holland Tack Factory building’s penthouse, guru Josh Kirk marshals a corps of core-crunching fitness experts. Inline Private Training's small class sizes help the tip-top team condition each student with a more personal touch and protect overstrained socialites from having to remember a slew of fellow classmates’ names. The studio furnishes students with mats and equipment, including toning balls, magic circles, foam rollers, and resistance bands. Clients train safely and effectively under a toned tutor's watchful eye, achieving hydra-like flexibility and a core strength to rival the golden apple that broke Hercules' teeth.

Though Inline Private Training sometimes features a discount online, this Groupon still offers the best deal available.