This article focuses on the unprecedented jump in life expectancy that occurred in the first third of the twentieth century and the corresponding revolution in Americans' attitudes toward aging and death. Rising life expectancy had many causes, including better nutrition, a reduction in epidemic diseases through vaccinations and modern sanitation measures, and successful educational campaigns aimed at reducing infant mortality. Despite the broad, society-wide causes of rising life expectancy, however, Americans during these decades overwhelmingly described life extension as a matter of personal, not social, responsibility. This new emphasis resulted in large part from the growing prominence of chronic diseases, which responded in a way epidemic diseases never could to individuals' decisions and habits. As it came to seem that long life and, by extension, prolonged youth were attainable by those who made good living choices, Americans increasingly described aging and even death itself as phenomena that were determined, to an extent unimaginable a few decades earlier, by willpower. This powerful series of associations, between youth, health, and willpower on the one hand and between aging, death, and laziness on the other, would profoundly shape U.S. society and social policy throughout the century and beyond.