People, through their bodily actions, engage in sensorimotor loops that connect them to the world and to their own bodies. People's brains integrate the incoming sensory information to form mental representations of their body appearance and capabilities. Technology provides exceptional opportunities to tweak sensorimotor loops and provide people with different experiences of their bodies. We recently showed that real-time sound feedback on one's movement (sonic avatar) can be used for sensory alteration of people's body perception, and in turn provoke enhanced motor behaviour, confidence and motivation for physical activity (PA) in people while increasing their positive emotions towards their own bodies. Here we describe the design process of a wearable prototype that aims to investigate how we can overcome known body-perception-related psychological barriers to PA by employing action-sound loops. The prototype consists of sensors that capture people's bodily actions and a gesture-sound palette that allows different action-sound mappings. Grounded in neuroscientific, clinical and sports psychology studies on body perception and PA, the ultimate design aim is to enhance PA in inactive populations by provoking changes on their bodily experience.