Behavioral Exposure for Interoceptive Tolerance (BE-FIT) is a mechanism-informed behavioral intervention to target exercise anxiety. The three primary components of BE-FIT include: (1) exposure to feared bodily sensations and exercise; (2) prevention of safety behavior use before/during/after exercise, and (3) use of a wrist-worn activity monitor for physical activity (PA) feedback and activity goal setting. Evidence from the investigators' Stage I trial indicated that BE-FIT is feasible, acceptable, and safe and produced reductions in exercise anxiety and increased exercise outcomes (short-term moderate-to-vigorous intensity physical activity and steps/day). The investigators' present aim is to conduct a Stage II randomized-controlled trial to further evaluate the efficacy of BE-FIT in decreasing exercise anxiety in cardiac rehabilitation (CR) patients and examine whether changes in this target yield successive changes in exercise adherence outcomes.