RecruitingBehavioural interventionPromoting Active Living Among People With Metastatic Breast CancerIndividuals with metastatic breast cancer are living longer but often face persistent fatigue, functional decline, and psychological distress. Physical activity is generally safe for this population and may alleviate symptom burden. Yet, limited interventions are tailored to the unique and needs and preferences of this population. This study aims to evaluate the acceptability and feasibility of a mindfulness- and acceptance-based physical activity program designed to support mental, social, and spiritual well-being among people with metastatic breast cancer. A single group, pretest-posttest trial (N=38) will be conducted to inform scalable strategies to promote active living and enhance quality of life among people with advanced cancer.