Background Despite the favorable effects of behavior change interventions on diabetes risk, lifestyle modification is a complicated process. In this study we therefore investigated opportunities for refining a lifestyle intervention for type 2 diabetes prevention, based on participant perceptions of behavior change progress. Methods A 30 month intervention was performed in Dutch primary care among high-risk individuals (FINDRISC-score ≥ 13) and was compared to usual care. Participant perceptions of behavior change progress for losing weight, dietary modification, and increasing physical activity were assessed after18 months with questionnaires. Based on the response, participants were categorized as ‘planners’, ‘initiators’ or ‘achievers’ and frequencies were evaluated in both study groups. Furthermore, participants reported on barriers for lifestyle change. Results In both groups, around 80% of all participants (intervention: N = 370; usual care: N = 322) planned change. Except for reducing fat intake (p = 0.08), the number of initiators was significantly higher in the intervention group than in usual care. The percentage of achievers was high for the dietary and exercise objectives (intervention: 81–95%; usual care: 83–93%), but was lower for losing weight (intervention: 67%; usual care: 62%). Important motivational barriers were ‘I already meet the standards’ and ‘I’m satisfied with my current behavior’. Temptation to snack, product taste and lack of time were important volitional barriers. Conclusions The results suggest that the intervention supports participants to bridge the gap between motivation and action. Several opportunities for intervention refinement are however revealed, including more stringent criteria for participant inclusion, tools for (self)-monitoring of health, emphasis on the ‘small-step-approach’, and more attention for stimulus control.