Much research has addressed behavior change but has tended to focus on short term changes. This study aimed to explore the mechanisms behind sustained changes in behavior and involved qualitative interviews with 34 `success stories' who had either lost weight through changes in diet and exercise (n = 24) or stopped smoking (n = 10) and had maintained this change for at least 3 years. The results showed that the majority described how their sustained behavior change had been triggered by a significant life crisis relating to their health, relationships or salient milestones. This initial change was then translated into sustained change if three sustaining conditions were met: the function of the unhealthy behavior was disrupted, the individual perceived that their choice over carrying out the unhealthy behavior had been reduced and they adhered to a behavioral model of their problem. Further, these conditions functioned by enabling a process of reinvention with participants showing a shift in identity toward a new healthier self. The results are discussed in terms of self-regulation and the establishment of a new post-crisis healthier equilibrium