To prevent cardiovascular diseases, eHealth solutions may be used as tools, involving health care consumers in the set-up of their prevention plan, a fundamental condition for improving their long-term adherence to the plan. This paper presents the first step in a web platform design aiming to support the co-elaboration by health care consumers and clinicians of personalized prevention plans. Applying a user driven innovation approach, first, a questionnaire and semi-structured interviews were combined to identify clinicians' needs. Then, three focus group sessions with consumers and clinicians were organized to identify their needs, creating the system workflows, its graphical user interface, and its navigation paths, with the best ideas shaped by paper mockups. An interactive mockup was designed including 30 screens (ex. user dashboards, desk for co-elaborating plan). This user driven approach enabled to design not only the technology and its graphical user interface, but also a prevention plan design process.