Many technologies for promoting physical activity (PA) give limited importance to critical variables for engagement in PA, such as negative body perceptions. Here, we aim to address this gap by incorporating barriers and experienced body sensations into the design process for wearables and body-based devices thus expanding the design space for such technologies. We first report four co-design workshops with physically inactive participants (n=9); in these workshops, we explored tangible tools (i) to sensitize people to body sensations experienced when facing barriers to PA and (ii) to ideate how haptic and auditory feedback could transform body sensations to increase body-awareness and engagement in PA; results show several interactive sensorial patterns with potential to inform the design of body transformation wearables. These were validated through a follow-up workshop (n=13 participants) and reflections based on insights from a literature review. Our findings are significant for the design of ubiquitous technology to support and initiate PA in everyday contexts through a novel approach of transforming body perceptions/ sensations related to PA barriers. We contribute design inspirations and cards for identifying barriers to PA and to empower designers and researchers to integrate them early in the design process.