Since December 2022, children and adolescents in the Pediatric Hematology, Oncology, and Stem Cell Transplantation department at University Hospital Aachen have had the opportunity to engage in physical activity. Through an individualized, health-promoting, and playful exercise program, participants’ strength, endurance, flexibility, and coordination are improved. Depending on the age and daily general condition of the children and adolescents, the program can be adapted—from gentle mobilization exercises while lying down, to active and playful activities on the ward, and even to more intensive sports activities outside the ward.