Don’t overdo it. Runners of all levels fall victim to the too’s—“too much, too soon, too hard,” says Dr. William Roberts, medical director for the Twin Cities Marathon in Minnesota. Start slowly, running half a mile, then walking half a mile—or walking a block, then running a block. People who do too much too quickly can develop problems like tendonitis in their heels or knees. For the average runner, a half hour five times a week is enough.

Don’t postpone a doctor visit. “People are notorious for trying to run through their pain,” says Dr. Tyler Cooper, a physician at the Cooper Clinic in Dallas and coauthor (with his father, Dr. Kenneth Cooper) of “Start Strong, Finish Strong.” “Be proactive. Go to the doctor before it gets bad. A lot of times just put-ting some orthotics [special inserts] in your shoe can change everything.”

Stretch and strengthen. Strong, flexible muscles provide the best back support. “God created us with a back brace: it’s the muscles in our back and stomach that help support our spine,” says Darrell Barnes, a certified athletic trainer at St. Vincent Sports Performance Center in Indianapolis. The National Athletic Trainers’ Association’s most recent recommendations to combat lower back pain call for paying attention to posture, standing up straight, always warming up first, getting a good night’s sleep on a firm mattress that doesn’t sag, adding aerobic exercise and using proper lifting technique (standing with a wide stance and a slight bend at the hips and knees, tightening the stomach and keeping the back flat).