Many previous studies have assessed the aging process by measuring clinical and functional variables. To supplement that quantitative understanding, we asked older people what constitutes their health and contributes to it. Using grounded theory-type methods, we analyzed semi-structured interviews with 22 study subjects, who were randomly selected from among those whose reported perceived health differed from that predicted by a regression model constructed from data from a randomized trial of a primary care intervention. We focused on disparate cases to identify factors that best discriminate between more and less healthy aging. Interview questions targeted perceptions of health; well-being; valued abilities, activities, and relationships; social support; control; sense of coherence; and personal outlook. A model of healthy aging emerged. To these older people health meant going and doing something meaningful, which required four components: something worthwhile to do, balance between abilities and challenges, appropriate external resources, and personal attitudinal characteristics (e.g., positive attitude vs. "poor me"). By reframing healthy aging in older people's own terms, this model encourages interdisciplinary support of their desired goals and outcomes rather than only medical approaches to deficits and challenges.