A growing body of evidence from Psychology and Sport Sciences shows that physical activity can be a cost-effective and safe intervention for the prevention and treatment of a wide range of mental and physical health problems. Research in domains such as the Internet of Things (IoT), wearables and persuasive technologies suggest that a coach intended to promote physical activities needs to provide personalized interaction. In this paper we introduce the WE-nner (pronounce “winner”) framework for designing an automated coach promoting physical activity which supports interactions between the user and a smart wearable that are: (1) personalized to the user, (2) dynamic (e.g. occurring during a physical activity), and (3) multimodal (e.g. combine graphics, text, audio and touch). We explain how we implemented this framework on a commercial smartwatch and provide illustrative examples on how it provides dynamic personalized and multimodal interactions considering features from user’s profile. Future directions are discussed in terms of how this framework can be used and adapted to consider theories and models from Psychology and Sport Sciences.