A Randomized Two-Arm Proof of Concept Study Testing A Novel Approach to Exercise Promotion Based on Affect-regulation

The goal of this clinical trial is to test the effect of an affect-based exercise prescription on moderate-vigorous physical activity participation among survivors of breast cancer who completed primary treatment within the last 5 years. The main questions it aims to answer are:

1. Do at least 50% of participants assigned to the affect-based exercise prescription engage in ≥90 minutes of moderate-vigorous physical activity by the end of 12-weeks follow-up? 2. What level of satisfaction do breast cancer survivors who receive the affect-based exercise prescription report relative to breast cancer survivors who receive an effort-based exercise prescription. 3. What proportion of participants assigned to the affect-based exercise prescription stay enrolled in the study relative to the number of participants who stay enrolled in the effort-based exercise prescription.

All participants will:

* Be assigned to either the Affect-based exercise prescription or the Effort-based exercise prescription. * Participate in two meetings with a member of the study team meant to help them get started increasing weekly exercise. These meetings are the same for all participants. * Be asked to wear an activity monitor and respond to brief surveys for 10 straight days at 4 points in time: Baseline, 2weeks, 6weeks, and 12weeks.