A Single Arm Pilot Study to Refine a Novel Approach to Exercise Promotion Based on Affect-regulation

Inclusion Criteria: * Within 5 years of completing curative treatment (surgery, chemotherapy, and radiation) for stage 0-III breast cancer * \<60 mins/week moderate-vigorous physical activity with no major changes for the past 6-months * Own an Android or iPhone smartphone and willing to use the smartphone to complete app-based surveys during assessment periods * Willing to wear the ActiGraph monitor during assessment periods * Access to internet to complete REDCap survey assessments Exclusion Criteria: * Non-English speaking/not able to read English * Evidence of major contraindications for exercise (informed by the 2020 Physical Activity Readiness-Questionnaire (PAR-Q)+) * Currently pregnant * History of severe mental illness or currently taking mood stabilizing medications (antipsychotics, anticonvulsants, or lithium) * Evidence of moderate-severe depressive symptoms (indicated by a score ≥10 on Patient Health Questionnaire-8) * Evidence of moderate-severe cognitive impairment (indicated by a score \< 3 on a 6-item cognitive screener) * Evidence of clinically significant substance use as indicated by a score of ≥2 on the CAGE-AID screener