Age

18–any

Sex

ALL

Healthy volunteers

Not accepted

≥18 years old
Within 5 years of completing primary cancer treatment (surgery, chemotherapy, and radiation) for Stage 0-III breast cancer
\<60 mins/week moderate-vigorous physical activity (MVPA) with no major changes for the past 6- months
Own an Android or iPhone smartphone (or tablet) and willing to use it 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

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 the 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.

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