As we push for better health care and longer lives, Gregory Rodriguez writes that we should think about the societal consequences of having so many old people hanging around. "No one wants to die young. No one wants to face the last years of life infirm and fragile. But if Japan, where ancestors are revered, is plagued with unhappy seniors, what does it bode for us?" he asks. "You could make it to 100, with consequences as onerous as the ones you ate right and exercised to avoid."