Bad backs. Carpel tunnel. Knee problems. Musculoskeletal issues are the single biggest cause of lost workdays, affecting 1/3 of all employees. Sports medicine expert and author Dr. Jordan Metzl has a prescription that is more potent, accessible, and effective than any drug: exercise. He shares simple strategies designed to make a big impact on your everyday life, and those of your employees at CNBC's @Work Summit.