The introduction of social assistive robots is a promising approach to enable a growing number of elderly people to continue to live in their own homes as long as possible. Older people are often an excluded group in product development; however this age group is the fastest growing segment in most developed societies. We present a participatory design approach as a methodology to create a dialogue with older people in order to understand the values embodied in robots. We present the results of designing and deploying three participatory workshops and implementing a subsequent robot mock-up study. The results indicate that robot mock-ups can be used as a tool to broaden the knowledge-base of the users' personal goals and device needs in a variety of ways, including supporting age-related changes, supporting social interaction and regarding robot aesthetic. Concerns that robots may foster inactivity and laziness as well as loss of human contact were repeatedly raised and must be addressed in the development of assistive domestic robots.