Background: There is widespread evidence of the health and wellness benefits associated with moderate physical activity, and lack of engagement with these behaviours remains a significant contributor to the burden of chronic disease in the US adult population. There are clear benefits to identifying motivational factors that facilitate increased personal adherence to physical activity behaviours. Objective: This study explored motivational influences on personal adherence to physical activity by examining the factors related to the behaviours of participants in an organised walking event. Design: Cross-sectional survey involving items for demographic variables, walking habits, perceived wellness, fulfilment of psychological needs, presence of chronic illness and motives for physical activity. Setting: The study sample included participants in a large US Midwestern walking event (N = 345) across a variety of demographic characteristics. Method: Study participants completed an online survey that gathered information related to personal demographics, behaviours and sources of motivation as measured by the Motives for Physical Activity Measure--Revised scale. This instrument was developed within the context of self-determination theory to measure different motives for implementing behaviours associated with physical activity. Results: Findings revealed different intrinsic (competence, enjoyment and social) and extrinsic (fitness and appearance) motivational influences on participation in walking events that varied based upon demographic characteristics. Conclusion: Motives for participation in walking events, as a mode of health promotion, are influenced by demographic characteristics and health states, and may be relevant for focused efforts to promote engagement with physical activity programming.