We are spending more and more time seated at work, which increases the risk for health problems. Behaviour change support systems that encourage breaks and stretching at work have been used as interventions to try to reduce these problems. No previous studies had looked at how these systems were used for long periods of time. In this qualitative study based on ten interviews, we aimed for expanding our understanding of long-term usage of such systems by studying one called ‘Efons’. The results indicate that the main factors influencing long-term usage are timely reminders, the impact that the stretching exercises has on the users’ health and the education of the user about health recommendations. We also found elements we argue have the ability to influence long-term usage and currently do not exist in the system studied or its context of use, such as adapt the system to the needs of the user or provide education about why these systems are useful.