If you want a cool and sexy workout, consider taking beginning or intermediate roller derby classes with the L.A. Derby Dolls. All of the hits are real, and if you're skating with someone you care about, hitting her the hardest while on the track proves that you love her enough to want to make her stronger for the experience. Men are welcome, but it's exclusively a woman's world when it comes to the competition circuit (men can become referees). Once you're in, you're way into a rich subculture with many rollers better known to one another by their roller derby aliases. The vibe is decidedly insular but more than worth the cost of immersion.
Credit: Kylie Krabbe