We define “frequent walkers” as people who walk over one hour in public space on most days of the week. Because they have successfully undergone mode shift, such pioneers have the potential to initiate change towards sustainable transportation at population level. This project seeks to understand how and why they became frequent walkers, how they integrate walking into their schedules, and what they perceive as facilitators or hindrances. After a quantitative phase, this qualitative phase analyses semi - structured interviews with 35 adult frequent walkers in Geneva and Lausanne. We found that most – but not all – of the walking is r elated to daily commuting. Concern with one's health and well - being are key motivators. Time - management strategies such as getting up earlier in the morning and using alternative routes – a direct route in the morning, a scenic route in the evening – are hallmarks of frequent walking in this population. Facilitators include the presence of parks and green spaces. Hindrances are road traffic, narrow or missing pavements (sidewalks), and traffic lights. Most respondents expressed aversion towards noise, air pollution, and – especially – tobacco smoke.