RecruitingBehavioural interventionExercise to ReGain Stamina and Energy (The EXERGISE Study)About 20%-70% of breast cancer survivors experience fatigue after cancer therapy. Because epidemiologic evidence shows that old age is a risk factor for fatigue in adults with cancer history, older breast cancer survivors suffer from even more fatigue than younger survivors. The purpose of this study is to test types of walking exercise interventions and their ability to reduce fatigue in older breast cancer survivors.