Pure Power Boot Camp, New York

Clad in fatigues and soaking in sweat, the denizens of Pure Power Boot Camp lift logs, climb walls, and navigate obstacle courses. If it sounds like military boot camp, that's no accident; each of the drill instructors are current or former military members. Presided over by Lauren Brenner—who became a personal trainer at 16 before playing Division I tennis and working as a trainer for the Syracuse men's basketball team—each instructor leads a platoon that trains together multiple times per week. Pure Power Boot Camp's boot-camp training is ideal for adventure races like Tough Mudder, Spartan Race, or Warrior Dash as it incorporates real obstacles and situations. After their initial training, members can enroll in maintenance courses that help them keep their new bodies in shape and offer an excuse to see the climbing wall with which they fell in love.