Lifestyle factors have been linked to the risk of developing many common malignancies and, increasingly, to prognosis. Observational evidence has shown a relationship between so-called energy balance factors (ie, diet, physical activity, and body weight) and risk of cancer recurrence and mortality in cancers of the breast, prostate, colon and, perhaps, other cancers. Interventional work has shown that individuals who make favorable changes in these lifestyle factors after cancer diagnosis feel better, experience less fatigue, and may possibly even decrease risk of cancer recurrence. Other lifestyle behaviors, such as smoking and alcohol consumption, have also been linked to the development of common cancers and may have important health consequences for cancer survivors. This article reviews the evidence that links lifestyle factors to cancer outcomes, provides clinical recommendations for cancer survivors, and describes future directions for lifestyle research in cancer survivors.