The National Exercise Referral Scheme (NERS) is a Public Health Wales (PHW) funded scheme which has been in development since 2007. The Scheme targets clients aged 16 and over who have, or are at risk of developing, a chronic disease. The scheme is centrally managed by the Welsh local Government Association. NERS is an evidence-based health intervention incorporating physical activity and behavioural change techniques to support referred clients to make lifestyle changes to improve their health and wellbeing. The principal aims of the scheme: To offer a high quality National Exercise Referral Scheme across Wales To increase the long term adherence of clients to physical activity To improve the physical and mental health of clients To determine the effectiveness of the intervention in increasing clients’ activity levels and improving their health.