Background: There is a need to better understand implementation processes of health interventions. This study describes the implementation of a multicomponent intervention to improve diet and physical activity among adults with intellectual disabilities, viewed from the perspectives of staff and managers. Materials and Methods: All health ambassadors (n = 12), appointed among staff and managers (n = 5) taking part of a health intervention in community residences in Sweden, were interviewed with a focus on barriers and facilitators regarding implementation of the intervention. Data were analysed using content analysis. Results: The overarching theme describes the importance of supporting motivation for change among managers, caregivers and residents. The experiences of the implementation process are described in four main categories: intervention characteristics, individual commitment, organizational capacity and societal factors. Conclusion: The implementation can be facilitated by a programme meeting perceived needs, a flexible and participatory approach, external input and an extensive preparation phase.