As the name might suggest, Function Factory is a gym whose trainers believe in the power of functional fitness. At this no-nonsense Mission Valley fitness center, certified personal trainers help clients employ a whole-body approach to working out, eschewing traditional machines for functional, balance, and body-weight exercises that train through resistance. Clients burn fat and build muscle, whether they take personal training sessions, small group classes, or even power yoga sessions. The trainers are also passionate about helping those who have been injured get back into shape and training athletes for competition. Outside of guided training, the gym's equipment is available at all times for members who'd like to work out on their own.