Introduction An active and engaged lifestyle is supported as being beneficial for brain health. Activities comprising physical, mental and social demands, or combinations of those, are of particular interest, and have been the focus of specific interventions. Exploring how older people engage with such community-based activities, including facilitators and barriers to participation, may help improve the success of future translational activities. The purpose of this study was therefore to identify factors that enabled or hindered activity engagement by conducting focus groups with people who had been supported to take up a new activity as part of an intervention study. Materials and methods Twenty-seven older adults aged 65–86 (56% female) who had completed an activity-based intervention study participated in three focus groups. Discussions explored their experiences of taking up a new activity, including facilitators and barriers to their engagement, and their perceptions of any benefits. Results Thematic analysis grouped participants’ responses into five themes: positive aspects and facilitators of engagement in a new activity; challenges and barriers to engagement; ageing being a facilitator and a barrier to engagement; differential effects of activities on participants’ health and wellbeing; and general project feedback (including opinions on study design). Discussion and conclusions Participants’ experiences and expectations included positive (e.g., enjoyment, socialisation) and negative factors (e.g., lack of confidence, other commitments, class costs and poor structure), consistent with previous research on social participation and engaging with new learning opportunities. Future studies should also consider those who do not readily participate in leisure activities to address earlier barriers. It is important that older adults have access to potentially beneficial activities and local authorities should prioritise increasing their provision.