Inclusion Criteria:  Hong Kong residents aged ≥ 18 years Cantonese language fluency and readability A Patient Health Questionnaire 9 items (PHQ-9) score of at least 10, indicating a moderate level of depression Possession of an internet-enabled mobile device (iOS or Android operating system) Willingness to provide informed consent and comply with the trial protocol  Exclusion Criteria:  Current serious suicidal risk (non-fleeting intent or plan) as assessed by a PHQ-9 Item 9 score > 2 (referral information to professional mental health services will be provided) Any medical or neurocognitive disorder(s) that makes participation unsuitable based on the team's clinical experience or interferes with adherence to the lifestyle modification (e.g., where exercise or a change in diet are not recommended by physicians) Current involvement in lifestyle changes supervised by professionals Unstable medication or current participation in any psychotherapy for depression Pregnancy Hospitalization Current participation in any other trial(s)