After a year of boot camp workouts elsewhere, we thought we were ready for this. Then the CrossFight class started. Running, crawling, kicking, punching, push-ups, sit-ups, jump-rope, weights. It's a killer 90 minutes that tests every muscle in the body and produces more sweat than a group hug at NFL training camp. At a dojo tucked into a woodsy corner of Bachman Lake, martial arts master Dr. Nick Chamberlain and Canadian Olympic boxer Martin Mazzera take students through an intense, well-thought-out program of exercise that combines aerobics, plyometrics, interval training, self-defense, kickboxing and martial arts. Halfway through each class, everyone heads toward the lake for a "horse and rider" run (or in our case, slog) up and down a steep hill. In 90 days the training significantly pares fat, improves conditioning and strength, and takes students from slugs to sluggers. Sounds grueling—and it is—but it's also surprisingly fun. And the friendly atmosphere at the studio makes out-of-shape newcomers feel welcome. Students range from schoolkids to women in their 60s. Best part of the workout? When it's over you feel like you've really taken that first step toward getting in the best shape of your life.