Despite its accomplishments, modern medicine has made little progress in combating the age-related ailments that kill the majority of people: heart disease, cancer, Alzheimer's disease, and type 2 diabetes. It intervenes much too often with remedies that are far too late to be useful, prolonging life at the expense of health span or quality of life. We must replace this archaic paradigm with a personalized, proactive approach to longevity that entails...