 At baseline and 12 and 26 weeks thereafter, the following assessments will be performed: measurement of physical activity with an accelerometer, measurement of body composition weight, BMI, fat percentage as measured with the skinfold measurements, parameters of metabolic syndrome this includes measuring waist circumference and blood pressure, drawing blood to measure fasting blood glucose, high density lipoprotein and triglycerides. In addition, filling out questionnaires on general physical activity ALCOS and PA self-efficacy PA self-efficacy questionnaire, health-related quality of life including satisfaction EORTC QLQ-C30, the EORTC BR23 and single question on satisfaction with life will be part of the study. Information on these questionnaires can be found in Appendix 5. 