Resilience Buddy: A Multi-System Mobile Intervention for Mental Well-Being—Development and Pilot Evaluation

Background/Objectives: Digital interventions can promote mental health, and resilience is a key target for prevention. Resilience is often treated as an individual trait, overlooking the relational, material, and structural conditions that shape adaptation. The Multi-System Model of Resilience (MSMR) views resilience as a process that arises from three interacting systems (internal, intermediary, and external) across three levels of need (essential, situational, and actualization). This study describes the development of Resilience Buddy, a mobile intervention based on this model, and evaluates its usability, participant feedback on acceptability, and preliminary pre- to post-intervention changes in resilience and psychological distress. Methods: A single-arm formative pilot was conducted with adults who completed pre- and post-intervention assessments. The app includes 10 modules. The first is an introductory self-monitoring module, and the remaining nine are learning modules aligned with the model domains. Each learning module follows the same five-part sequence of values, inform & inspire, transcend, act, and link (VITAL). Outcomes were measured with the MSMR Inventory, the 12-item General Health Questionnaire, and the 4-item Usability Metric for User Experience. Data were analyzed with paired t tests, and Wilcoxon signed-rank tests were used as sensitivity analyses. Results: The analytic sample was 47 adults (mean age of 24.28 years, ranging from 19 to 45). Usability was moderate. Total resilience increased from pre to post (mean change of 7.23, p < 0.001), with the largest gains in the external-system domains. Psychological distress decreased (mean change −5.27, p < 0.001). Gains in resilience were associated with reductions in distress using Pearson’s correlation, but not Spearman’s. Conclusions: Resilience Buddy appears usable, acceptable, and associated with promising early improvements in resilience and distress. Controlled trials are needed to test efficacy and identify which domains respond most to digital intervention.