Despite the undeniable benefits of physical activity during and beyond cancer treatments, patients do not always undertake and/or maintain it. The aim of the study is to identify, describe and understand the barriers and facilitators of physical activity practice among adults arriving at the end of treatment for solid cancer, in precarious situations, living in Seine-Saint-Denis.The study was conducted using a descriptive qualitative phenomenological method involving semi-directed interviews with 23 participants during and beyond cancer.Multiple-level factors (micro, meso, macro) are involved in active behavior of patients. Three main facilitators were identified: perceived benefit, social support, and urban planning. Three barriers are identified: (1) physical and psychological disorders whether or not related to cancer and its treatment, (2) precariousness, organizational constraints, unfavorable social environment, (3) lack of coordination, lack of accurate and appropriate information, lack of realistic referral to physical activity offers.A diversity of representations, combinations of factors, and experiences are described. Getting people with cancer to engage in and maintain long-term physical activity is a complex task, requiring multidisciplinary action on all socio-ecological factors.