Functional fitness, a concept that’s been around since we were cavemen, is now gaining mainstream respect—reverence really—among exercise experts who not long ago underestimated its importance. For years, the trainers harped on their clients to work a muscle or muscle group to build maximum strength or tone. But our muscles rarely work alone, and therein lies the foundation of functional fitness. The idea is simple: exercises that train your muscles, joints and senses to work together—not in isolation—as they do when you’re performing everyday tasks protect you against injury. More important they promote physical longevity, which means even if you eventually stop running marathons or dead-lifting 250 pounds, you’ll still be able to carry your laundry basket up the stairs, shovel your front walk, and play with your grandkids.