Most research studies seeking to understand walking and cycling behaviours have used cross-sectional data to explain inter-individual differences at a particular point in time. Investigations of individual walking and cycling over time are limited, despite the fact that insights on this could be valuable for informing policies to support life-long walking and cycling. The lack of existing longitudinal data, difficulties associated with its collection and scepticism towards retrospective methods as a means to reconstruct past behavioural developments have all contributed to this deficit in knowledge. This issue is heightened when the time frame extends to longer term periods, or the life course in its entirety. This paper proposes and details a retrospective qualitative methodology that was used to study individual change and stability in walking and cycling within a life course framework.