RecruitingBehavioural interventionFeasibility of High Intensity Interval Training in Survivors of Childhood, Adolescent, and Young Adult Hodgkin LymphomaThis pilot study evaluates the feasibility of a 12-week high intensity interval training (HIIT) program in survivors of childhood, adolescent, and young adult Hodgkin lymphoma within 24 months of completing treatment. Preliminary efficacy of the HIIT intervention for improved cardiorespiratory fitness, body composition, physical function, autonomic response to exercise, peripheral neuropathy, biological aging markers, and physical activity will also be evaluated. Primary Objective: To determine the feasibility of a 12-week high intensity interval training (HIIT) program in survivors of childhood, adolescent, and young adult Hodgkin lymphoma within 24 months of completing treatment. Feasibility will be assessed by: * Participation Rate: Number of eligible survivors approached who enroll. * Completion Rate: Number of scheduled HIIT sessions attended and number of enrolled participants who complete post-intervention testing.