as diabetes, obesity and hypertension. Despite these health-related benefits, perceived costs such as privacy concerns play a crucial role for the persistent success of fitness trackers. To understand which factors influence the continuous use of fitness trackers and investigate the particular role of privacy concerns in this tension field, we conducted 16 semi-structured interviews. Based on a rigorous iterative thematic analysis, where we constantly match our codes with literature, we develop a thematic map that identifies three main user determinants (Perceived Benefit, Perceived Privacy and Perceived Deficiency) and 12 sub-themes. Our findings propose a new theoretical construct (Perceived Relativity), a newly detected tracking motive (Social Tracking) and provides the prerequisites for user agreements to health data collection. By this means, we enable researchers to uncover and visualize user perceptions concerning fitness trackers and provide practitioners with workable suggestions for ensuring their continuous use.