Aim: This study was aimed to explore the mechanisms of long-term behavior changes to a healthier lifestyle. Materials and Methods: We conducted focus group interviews with a sample of 18 adults without further selection criteria and applied a top-down thematic analysis approach to extract the determinants of long-term health behavior change. Result: The results showed that long-term health behavior changes only occurred as a response to life events that force individuals to abandon established habits. These triggers accrued from the interplay of three life course elements: The life phase, a change in external living conditions (e.g. the social environment) over time, and internal motifs (past experience, future goals, and perceived immediate payoff). Conclusion: Our results are discussed in the context of sociological lifestyle theories, suggesting that longterm lifestyle change follows from a disturbed equilibrium between external determinants and identity cues.