Online Physical Activity and Health Counseling for Survivors of Childhood Acute Lymphoblastic Leukemia

26 weeks online high intensity functional training, performed 1-2 times per week + access to a LIFESTYLE PHYSICAL ACTIVITY WEBSITE including 8 modules; 1) Welcome, information about the intervention and the aims of the study, 2) Living a physically active lifestyle, 3) Sedentary behavior, 4) General exercise recommendations, 5) How to stay motivated, 6) Strength training, 7) flexibility, balance, and coordination, and 8) Healthy eating + weekly motivational counseling