Recent research emphasizes the high potential of using the office environment as an opportune setting to improve the physical activity level of individuals. A design research artefact was developed to investigate the underlying variables influencing the effect of social feedback on physical activity at work. We adopt a mixed-method approach, combining an online questionnaire (N =103) with two field studies focusing on the social feedback modalities of social awareness (N=8) and social collaboration (N=12) were tested in a 3-week field-study. Results show a positive effect of visualizing the feedback on the activity pattern of individuals, while creating awareness and opportunities for individuals to be active on both an individual and social level. With our work, we provide insights on the role of social feedback, while giving both insights and recommendations for design intervention aiming to improve the physical activity pattern of office workers.