Recent numbers display a 85% survival-rate in children after a very harmful disease such as cancer. However, the survivors still experience mild to severe side effects of the primary disease or treatment. A long time follow-up in the University Hospital of Ghent in children with cancer displays important long term side effects such as: reduced muscle strength; reduced endurance capacity; reduced exercise tolerance; fatigue; disturbed body composition with increased risk for obesity and/or diabetes and osteoporosis; and neuropathic damage and myopathy. These physical complaints have a significant impact on the activities and participation in daily living. The purpose of this interventional study is to create a rehabilitation program for children after acute cancer treatment. The goal is to minimalize the previous described long term side effects of the disease. The current study should allow us to determine the effects of the intervention at the level of functioning, activities and participation. In addition, we account for the environment and personal factors as described by the International Classification of Functioning, disability and health (ICF-criteria). The study population consists of children between 8 and 11 years and adolescents of 12 to 21 years old. All participants receive a multidisciplinary treatment for 4 months, guided by a team which includes: oncologist, rehabilitation doctor, physical therapist, dietitian, psychologist, and occupational therapist. At the beginning of the multidisciplinary program, the participants receive psychoeducation, diet advice, tips for participation, fatigue, and psychological well-being. In general, the rehabilitation program focusses on reintegration at school and leisure activity. After the first assessment, an individually adjusted physical program consisting of strength and endurance training will be made. This physical program will be executed 3 times a week, 2 times guided by a physical therapist at the University Hospital or at a private practice, and ones a week by themselves at home recorded by an activity tracker. Follow-up is foreseen on monthly basis. Participants will undergo assessment 3 times: 1) baseline (T0); 2) after 4 months treatment (T1); 3) after 1 year follow-up (T2). The purpose of this program is to encourage patients at risk for increasing their healthy habits, exercise and participation in order to decrease long-term (side) effects.