Physical inactivity can contribute to serious chronic ill health effects such as heart disease, hypertension, obesity, type II diabetes, and even cancer (Centers for Disease Control and Prevention, 2017). Interventions designed to increase physical activity are needed to help address this socially significant issue. The current study was designed to replicate and extend past work to determine whether self-tailored deposit contracts could be used to increase physical activity (i.e., minutes exercised per week) at a gym for three sedentary adults using a changing-criterion design. Minutes exercised increased for all three participants, and participants met all of their goals across the 6-week intervention. In a follow-up, physical activity decreased but remained above that obtained during baseline. This research adds support to a growing body of literature showing that behaviorally based interventions such as self-tailored deposit contracts can be used to increase physical activity in gym settings with adults.