This research explored health decision-making processes among people recently diagnosed with type 2 diabetes. Our analysis suggested that diagnosis with type 2 was followed by a period of intense emotional and cognitive disequilibrium. Subsequently, the informants were observed to proceed to health decision-making which was affected by three separate and interrelated factors: knowledge, self-efficacy, and purpose. Knowledge included cognitive or factual components and emotional elements. Knowledge influenced the degree of upset or disequilibrium the patient experienced, and affected a second category, agency: the informants’ confidence in their ability to enact lifestyle changes. The third factor, purpose, summarized the personal and deeply held reasons people gave as they made decisions concerning their health, eating and exercising. We propose this model, grounded in informant stories, as a heuristic, to guide further inquiry. From these stories, the patient is seen as more active and the interrelated influences of knowledge, agency, and purpose, synergistically interact to explain changes in health behaviors.