Worldwide, over 1 million cases of breast cancer are diagnosed each year. In the USA, approximately 185,000 women are newly diagnosed annually. Nearly 90% of newly diagnosed cancer patients in the USA will live for 5 years beyond diagnosis and there are estimated to be 2.4 million breast cancer survivors currently living in the USA. There are unique challenges in meeting the medical needs of these survivors. Persistent impairment and increased medical risks can occur as a result of treatment, including changes to the cardiovascular, pulmonary, endocrine, immune, musculoskeletal, neurological and lymphatic systems. Physical activity can cause positive changes in each of these body systems. However, physiologic impairments and altered risks for cardiopulmonary, bone health, neurosensory and other outcomes among breast cancer survivors can cause confusion regarding the safety of returning to exercise after treatment. In this article, we review the adverse effects of cancer treatments on the body systems affected by and used to perform exercise, the risks of exercise among breast cancer survivors, the effects of exercise on persistent treatment toxicities, whether exercise may prevent recurrence or mortality, as well as providing guidance for exercise testing and prescription among breast cancer survivors.