Kettlebells and dumbbells line the walls. Giant tractor tires are scattered across the entrance. Thick yellow ropes dangle from the ceiling. In this bare-bones gym, trainers use this equipment and more during intense CrossFit classes. Workouts change daily to avoid repetition and keep exercisers motivated, and feature a slew of everyday movements. CrossFit preps participants for all manner of physical activity, sculpting all muscle groups to enhance speed, power, agility, and balance.