Cancer is a global health problem with over 10 million cancer survivors in the United States alone. Cancer and its treatments often produce side effects that undermine quality of life. The purpose of this article is to review research examining the effects of physical activity (PA) upon quality of life and disease prognosis in cancer survivors. We divide our review into PA studies focusing upon (a) quality of life during treatments, (b) quality of life during survivorship (after treatments), (c) quality of life during palliative care, and (d) disease prognosis end points. Compelling clinical trial data indicate that PA can improve quality of life end points during treatment and survivorship. Data during palliative care is limited. Observational data suggest that PA may reduce the risk of disease recurrence and extend survival in some cancer survivors. Research findings suggest that PA is an appropriate recommendation for most cancer survivors, although many research questions remain.