This study investigates how a web-based physical activity program can improve long-term health in children and adolescents with acute lymphoblastic leukemia (ALL). ALL is a type of cancer that affects the blood and bone marrow. The study focuses on participants who have shown a reduction or disappearance of symptoms after initial treatment.

Participants will engage in a web-based program designed to encourage regular physical activity. This program aims to help maintain a healthy weight and improve energy levels. Participants will use a device called an accelerometer to track their physical activity, which will be synced with an online account.

• Who can participate: Children and adolescents who are in their first remission from acute lymphoblastic leukemia can participate. They must have completed chemotherapy within the last 6 months and currently engage in less than 420 minutes of physical activity per week. Participants need access to a smartphone or computer with internet. Participants must be able to read and write English and cannot have had a hematopoietic stem cell transplant or significant concurrent diseases.
• Study details: Participants will use a web-based program to track and increase their physical activity. They will need to sync their physical activity data using a device that measures movement, called an accelerometer, with an online account. A parent or guardian must assist the participant with this process.