This paper reports on a research trial designed to evaluate the benefits of a health mentoring programme supported with a web and mobile phone based self-monitoring application for enhancing self-efficacy for self-management skills and quality of life for people with CF. This randomised, single-blind controlled trial evaluated two strategies designed to improve self-management behaviour and quality of life. Task-specific self-efficacy was fostered through mentorship and self-monitoring via a mobile phone application. Trial participants were randomised into one of three groups: Control, Mentor-only and Mentor plus mobile phone. Analysis and discussion focus on the experiences of participants through a methodology utilising descriptive statistics and semi-structured interviews. The results highlight the challenges of stimulating self-management behaviours particularly in adolescents and in the evaluation of the role of mobile applications in supporting them.