Using fitness trackers to generate and collect quantifiable data is a widespread practice aimed at better understanding one's health and body. The intentional design of fitness trackers as genderless or universal is predicated on masculinist design values and assumptions and does not result in "neutral" artifacts. Instead,\ ignoring gender in the design of fitness tracking devices marks a dangerous ongoing inattention to the needs, desires, lives, and life chances of women, as well as transgender and gender nonconforming persons. We utilize duoethnography, a methodology emphasizing personal narrative and dialogue, as a tool that promotes feminist reflexivity in the design and study of fitness tracking technologies. Using the Jawbone UP3 as our object of study, we present findings that illustrate the gendered physical and interface design features and discuss how these features reproduce narrow understandings of gender, health, and lived experiences.