Despite the proven health benefits of physical activity, only 48% of adults in New Zealand are physically active. There are many factors influencing individuals to be active. One of them is social influence, i.e., the effects others have on an individual's behaviour. Persuasive Technology is a relatively new research field, which explores how technology can influence the behaviour of its users. The purpose of this study is to investigate how technology can exert social influence to motivate and support physical activity. This paper presents a case study of a wellbeing initiative in a healthcare organization. The findings identify system requirements and social influence factors users perceive as essential in a system sup-porting the initiative. Four themes were identified as shaping the physical activity outcome of partici-pants: personal attributes, organisation, technology features and persuasive technology aspects. The results demonstrate that the persuasive elements in the form of social comparison, feedback, infor-mation/ advice and recognition motivate participants, but technology can be persuasive only in com-bination with the other factors. A model for the design of Persuasive Technologies is proposed for the design of a system to support the health initiative considered the case.