RecruitingBehavioural interventionExercise in Metastatic Breast Cancer: EMBodyThe purpose of this study is to study exercise in a novel population with indolent MBC (no progression on current therapy in prior 12 months and not receiving cytotoxic chemotherapy). The study team hypothesizes that delivering virtual, supervised, progressive intensity aerobic and resistance training exercise for 16 weeks in this population will significantly improve 1) cardiorespiratory fitness, functional status, and sarcopenia (low muscle mass), all established predictors of survival, and 2) patient- reported outcomes.