In the early years of life and during adolescence, physical activity is crucial for good development of motor skills. It is even more so for those children and young people who are forced to undergo anti-cancer therapies and therefore undergo long periods of hospitalization (often bedridden) and prolonged periods of physical inactivity. The research project Sport Therapy was born with the aim of demonstrating that, through targeted physical activity administered by the sports physician in collaboration with the pediatrician hematologist, it is possible to facilitate the full recovery of these patients, avoiding the high risk of chronic diseases related to a sedentary lifestyle and allowing them to better reintegrate, once healed, in their community of origin (school, sport and social relations). The research project Sport Therapy was born within the Maria Letizia Verga Center at the Pediatric Clinic of the University of Milan Bicocca, at the Foundation for the Mother and Her Child, San Gerardo Hospital in Monza. Every year, around 80 children and adolescents with leukemia, lymphoma or blood disorders leading to bone marrow transplantation are treated here.