RecruitingPhase 2Behavioural interventionStudy of Aerobic Training for People Receiving Chemotherapy for Breast CancerIn this study, investigators will compare standard Aerobic Training/AT with adaptive Aerobic Training/AT. Standard AT will be a fixed (unchanging) amount of walking each week, while adaptive AT will adjust the level of exercise depending on participants' response to the exercise. Investigators will see how both study approaches (standard AT and adaptive AT) affect participants' CRF.