We study the effect of subjective mortality beliefs on life-cycle behavior. With new survey evidence, we document that survival is underestimated (overestimated) by the young (old). We calibrate a canonical life-cycle model to elicited beliefs. Relative to calibrations using actuarial probabilities, the young undersave by 26%, and retirees draw down their assets 27% slower, while the model's fit to consumption data improves by 88%. Cross-sectional regressions support the model's predictions: Distorted mortality beliefs correlate with savings behavior while controlling for risk preferences, cognitive, and socioeconomic factors. Overweighting the likelihood of rare events contributes to mortality belief distortions.