Exercise can have significant benefits for breast cancer survivors during and after treatment. The general aerobic prescription is for moderate-intensity activity (50% to 75% heart rate reserve), 3 to 5 days per week, 20 to 60 minutes per session. Resistance training should also be incorporated into the programs. Psychological health is optimized by exercise that is enjoyable, develops new skills, incorporates social interaction, and takes place in a mind- and spirit-stimulating environment. Conditions that warrant prescription modification include fatigue and nausea, cytopenias, lymphedema, and bone metastasis. Postcancer exercise is facilitated by instilling a positive attitude toward exercise, confidence in overcoming barriers, and a supportive social environment.