 Weight gain is a common phenomenon among breast cancer patients receiving adjuvant chemotherapy as well as receiving adjuvant anti-hormonal therapy. While sufficient physical activity and limitation of the amount of weight gain is important for all breast cancer patients, it surely is for overweight and obese patients. The recently published national guideline oncological rehabilitation provides exercise goals, for physical training based on the Dutch PA guideline Nederlandse Norm Gezond Bewegen NNGB. It recommends to engage in moderate-intensity exercise e.g. brisk walking for at least 30 minutes a day, on at least 5 days a week. For people who are overweight Body Mass Index 25 kgm2 it is recommended to exercise at least 60 minutes at a moderate-intensity level, equal or more than 3 Metabolic Equivalent Task Hours 3 METh, on at least 5 days a week. However, only 61 of the general population, meets these guidelines 8 and among cancer patients this percentage is even less. This study aims to increase the percentage of overweight breast cancer patients treated with adjuvant anti-hormonal therapy that reaches the goal of the NNGB by the oncological rehabilitation program with 20. 