Aging is often associated with inevitable biological decline. Yet research suggests that subjective aging—the views that people have about their own age and aging—contributes to how long and healthy lives they will have. Subjective age and self-perceptions of aging are the two most studied aspects of subjective aging. Both have somewhat different theoretical origins, but they can be measured reliably. A total of 41 studies have been conducted that examined the longitudinal health effects of subjective age and self-perceptions of aging. Across a wide range of health indicators, these studies provide evidence for the longitudinal relation of subjective aging with health and longevity. Three pathways might explain this relation: physiological, behavioral, and psychological pathways. The evidence for behavioral pathways, particularly for health behaviors, is strongest, whereas only a few studies have examined physiological pathways. Studies focusing on psychological pathways have included a variety of mechanisms, ranging from control and developmental regulation to mental health. Given the increase in the number of older people worldwide, even a small positive change in subjective aging might come with a considerable societal impact in terms of health gains.