Background Evidence of the benefits of engaging in physical activity (PA) is strong, yet the number of older adults meeting the recommended 150 min/wk is low. Policy to increase uptake and adherence has focussed on the health benefits of PA, but may not be the most successful approach. Objective This qualitative study sought to ask older adults what the components of a successful intervention to promote PA would be, by asking active older adults what motivated them to be active and asking inactive older adults what might encourage them to change. Design, setting and participants Focus groups and semi‐structured interviews were held with 60 community‐dwelling older adults, aged 50‐87 years. Framework analysis was used to analyse the data, and themes congruent with a social ecological model of behaviour change were developed. Findings Five themes emerged that influenced PA engagement at multiple levels: individual; interpersonal; perceived environment; community or organizational; and policy. PA engagement was determined by attitude or health status for some participants, but for the majority, PA being enjoyable, sociable, affordable, accessible, flexible and seasonal were more important than the health benefits. Discussion and conclusions A social ecological model is presented, highlighting the fact that both motivated and unmotivated older adults need to have a range of appropriately labelled, appealing and accessible activities to choose from when thinking about engaging in PA. Policymakers and practitioners need to ensure that their offers of activity sessions are easy to access and easy to remain involved in.