Start powerlifting.
Credit: Photograph by Patrik Giardino

Typically, the average runner is about as likely to lift heavy weights as a powerlifter is to run 10 miles. Among the few runners who do pump iron, most perform lots of reps with light loads. Instead, pick up 45-pound plates, like five-time national champion Nick Symmonds does. He regularly bangs out six- and eight-rep sets of heavy lunges, step-ups, and power cleans.