Supporting exercise adherence through technology remains an important HCI challenge. Recent works showed that altering walking sounds leads people perceiving themselves as thinner/lighter, happier and walking more dynamically. While this novel approach shows potential for physical activity, it raises critical questions impacting technology design. We ran two studies in the context of exertion (gym-step, stairs-climbing) to investigate how individual factors impact the effect of sound and the duration of the after-effects. The results confirm that the effects of sound in body-perception occur even in physically demanding situations and through ubiquitous wearable devices. We also show that the effect of sound interacted with participants’ body weight and masculinity/femininity aspirations, but not with gender. Additionally, changes in body-perceptions did not hold once the feedback stopped; however, body-feelings or behavioural changes appeared to persist for longer. We discuss the results in terms of malleability of body-perception and highlight opportunities for supporting exercise adherence.