In my book,Good Money, I argue that the traditional retirement model—40 years of work followed by decades of withdrawal from it—is out of step with modern life and with what we know about human flourishing. Americans now livelonger livesthan any generation before them, as do othersaround the world, and many can expect15-20 yearsor more of retirement. Yet research repeatedly shows that leaving work entirely cansometimes leadto poorer physical health, cognitive decline, and even increased mortality if handled poorly. This is perhaps not surprising given that full retirement can lead to decreased physical activity, lower community engagement, and loss of a sense of purpose and direction.