Using a qualitative approach, the dimensions of subjective well-being of active older adults were outlined and ways identified through which they might be influenced by participation in physical activities. One-to-one and group interviews were used to collect the data. Using cross-case analysis, 17 main themes were identified. The following main dimensions emerged: developmental, material, physical, mental, and social well-being. The findings indicated that physical activity influences all dimensions of the subjective well-being of older adults, with the exception of material well-being. Physical activity appears to contribute to the mental health of older adults through maintenance of a busy and active life, mental alertness, positive attitude toward life and avoidance of stress, negative function, and isolation. The complexity of subjective well-being and the multiple roles of physical activity stress the need to extend qualitative research to sedentary older adults and the institutionalized elderly to explore the relationship between well-being and physical activity in later life.