Extant literature has largely not examined how users critically engage with their physical activity monitors, as objective data sense-making is often deemed superior to users' subjective realities. Our research, however, examines how middle-school youth encounter the representation of their data, as it is converted and actionable in an online game. This ethnographic study illustrates how youth negotiate conflicts between their data and embodied experience. Using a grounded theory approach, our analysis of interviews and focus groups reveals emergent categories of resistance such as youth evaluating the incompatibility of the device, disputing the device's step-count accuracy and syncing, and disputing the game's conversion of steps. In particular, we highlight the ways youth sometimes privileged their embodied recollections over the device's seemingly accurate data. The article also provides a case of a day during implementation when youth converged on a single form of resistance, game conversion, and examines their reasoning and alternate forms of data validation that we saw in-action on that day. Finally, we discuss benefits to learning and critical engagement that result from users' disputes and conclude by positing the promise in designing physical activity monitors for engagement, instead of exclusively persuasion or reward.