Aussie-FIT

Primary outcome [1] Changes in the quality of motivation for physical activity Assessment method [1] Behavioural Regulation in Exercise Questionnaire 3-6 (BREQ3-6) Timepoint [1] Assessed daily for 28 weeks across all study phases including: - Baseline phase (weeks 0 - 6) - Intervention phase (weeks 6 - 16) - Maintenance phase (weeks 16 - 28) Secondary outcome [1] Changes in affect Assessment method [1] Six items tapping positive and negative emotions from the Positive and Negative Affect Schedule Timepoint [1] Assessed daily for 28 weeks across all study phases including: - Baseline phase (weeks 0 - 6) - Intervention phase (weeks 6 - 16) - Maintenance phase (weeks 16 - 28) Secondary outcome [2] Changes in craving for substance use Assessment method [2] 3-item Craving Scale Timepoint [2] Assessed daily for 28 weeks across all study phases including: - Baseline phase (weeks 0 - 6) - Intervention phase (weeks 6 - 16) - Maintenance phase (weeks 16 - 28) Secondary outcome [3] Changes in physical activity Assessment method [3] Step counts and active minutes per day, measured by Fitbit Inspire 2 wireless activity monitors Timepoint [3] Assessed daily for 28 weeks across all study phases including: - Baseline phase (weeks 0 - 6) - Intervention phase (weeks 6 - 16) - Maintenance phase (weeks 16 - 28) Secondary outcome [4] Intervention feasibility and acceptability as a composite outcome Assessment method [4] A 7-item measure from Aussie-Fit will be used to assess the feasibility and acceptability of the intervention. In addition, study process data will be collected, including the number of people who agree to participate in the study, the number of people who sign consent forms, and attendance in the motivational intervention sessions Timepoint [4] End of intervention phase, 16 weeks after baseline