Lifestyle Program (Scalable Nutrition and Physical Activity) for the Improvement of Nutrition and Physical Activity in Stage 0-III Breast Cancer Survivors

Inclusion Criteria: * Previous diagnosis of stage 0-III breast cancer in the past 10 years at the time of enrollment * No evidence of recurrent or metastatic disease * No uncontrolled diabetes mellitus defined as glycosylated hemoglobin (Hgb A1C) \> 8% * No uncontrolled hypertension per Seattle Cancer Care Alliance (SCCA) standard of care * At least 60 days post final chemotherapy, biologic therapy, or radiation therapy and/or surgery. Current use of endocrine therapy is permitted (e.g., tamoxifen and aromatase inhibitors) * Access to phone for study contacts * Access to smartphone, tablet, or computer and internet to attend online session(s) and receive study electronic eHealth communication (text messages and access to website) * Willing and able to attend the online session(s) on Saturdays, or via online accessed videos, for up to 12 sessions in 6 months * Successfully complete all run-in activities, including at-home and over the phone assessments, 7 days of collecting physical activity data via accelerometer, and providing blood and stool sample * Willing and able to complete all study activities for 6 months after randomization * Participants must consume \< 5 servings of fruits and vegetables per day and/or engage in \< 150 minutes per week of moderate to vigorous physical activity, as assessed by brief questionnaires * Participants must have an Eastern Cooperative Oncology Group (ECOG) Scale of performance status score of 0 or 1 for performance status. * Signed physician approval for diet change and physical activity * Able to understand and willing to sign written informed electronic (e) consent in English Exclusion Criteria: * Participants must not be active smokers within the past 30 days. * Women must not be pregnant at time of enrollment