PurposeThe present study aimed to identify patients’ experienced barriers and facilitators in implementing physical activity programs for patients with cancer.MethodsWe interviewed 34 patients in focus-group-interviews from three different hospital-types. We included patients with cancer who were either receiving curative treatment or had recently completed it. Barriers and facilitators were explored in six domains: (1) physical activity programs, (2) patients, (3) healthcare professionals (HCPs), (4) social setting, (5) organization, and (6) law and governance.ResultsWe found 12 barriers and 1 facilitator that affect the implementation of physical activity programs. In the domain of physical activity programs, the barrier was physical activity programs not being tailored to the patient’s needs. In the domain of patients, lacking responsibility for one’s own health was a barrier. Knowledge and skills for physical activity programs and non-commitment of HCPs impeded implementation in the domain of HCPs. Barriers in the domain of organization included inconvenient place, time of day, and point in the health treatment schedule for offering the physical activity programs, inadequate capacity, inaccessibility of contact persons, lack of information about physical activity programs, non-involvement of the general practitioner in the cancer care process, and poor communication between secondary and primary HCPs. Insufficient insurance-coverage of physical activity programs was a barrier in the domain of law and governance. In the domain of physical activity programs, contact with peers facilitated implementation. We found no barriers or facilitators at the social setting.ConclusionsFactors affecting the implementation of physical activity programs occurred in various domains. Most of the barriers occurred in the domain of organization.Implications for Cancer survivorsAn implementation strategy that deals with the barriers might improve the implementation of physical activity programs and quality of life of cancer survivors.Electronic supplementary materialThe online version of this article (10.1007/s11764-019-00789-3) contains supplementary material, which is available to authorized users.