Over half of young adult cancer survivors do not meet physical activity (PA) guidelines. PA interventions can enhance health and quality of life among young adult cancer survivors. However, few exercise interventions have been designed and tested in this population. This study evaluated the feasibility and preliminary efficacy of a 12-week, Facebook-based intervention (FITNET) aimed at increasing moderate-to-vigorous intensity PA compared to a Facebook-based self-help comparison (SC) condition