The roles of motivational interviewing and self‐efficacy on outcomes and cost‐effectiveness of a community‐based exercise intervention for inactive middle‐older aged adults

= 0.16). Regression analyses found baseline self-efficacy predicted increased PA at 52 weeks, while baseline well-being did not. The relationship between self-efficacy and PA increased successively across time points. However, magnitude of participants' increased self-efficacy did not predict PA at any time point. Both pathways were cost-effective and cost -saving for participants aged ≥61 years from the short time horizon, with the MI pathway having greater ROI estimates. Overall, MI increased efficacy of a signposting PA intervention and was cost-saving for older adults.