Wearable activity trackers (WATs) have recently gained worldwide popularity, with over a billion devices collecting a range of personal data. To receive additional services, users commonly share this data with third-party applications (TPAs). However, this practice poses potential privacy risks. Privacy-enhancing technologies have been developed to address these concerns, but they often lack user-centered design, and therefore, are less likely to be directly related to users’ concerns and to be widely adopted. This study takes a participatory design approach involving 𝑁 = 26 experienced WAT users who share data with TPAs. Through a series of design sessions, participants conceptualized 19 solutions, from which we identified different promising design features, namely partial sharing, visualization, centralization, reminder, revocation, education, and TPA limit. We further discuss how these features can be combined to assist users in managing their data sharing with TPAs and, therefore, enhancing their privacy. This work makes an important contribution by offering user-centered solutions and valuable insights for integrating privacy-enhancing technologies into the WAT ecosystem.