ADAPT Micro-Randomized Trial

Inclusion Criteria: * Must be a patient within the Michigan Medicine clinical system with data available in the electronic health record after January 1, 2020. * Age \> 18 * Owns and is a daily user of an Android or iPhone smartphone with study supported operating software. * Understands English to enable informed consent, completion of study-related surveys, and compliance with study notifications. * Will be completing within 30 days or have completed in the last 30 days the cardiac rehabilitation program at Michigan Medicine based on one of the following indications: * Coronary artery disease (including acute coronary syndromes and stable angina) following percutaneous coronary intervention (PCI) * Coronary artery disease following coronary artery bypass surgery (CABG)\] * Valve repair or replacement (either surgical or percutaneous) * Coronary artery disease or an acute coronary syndrome not requiring revascularization Exclusion Criteria: * Orthopedic or neurological condition limiting ability to actively engage in moderate intensity physical activity (e.g., brisk walking) * Greater than mild cognitive impairment * Wrist too large to wear an activity tracker comfortably. This will be assessed by asking participants "If they have ever had difficulty wearing a watch in the past due to the band being too small." * Currently receiving palliative care and/or in hospice care * Severe valvular stenosis or regurgitation * Unrevascularized left main coronary artery disease (\> 50% obstruction on angiography) or proximal left anterior descending disease (\>70% obstruction on angiography). * Exercise-induced ventricular tachycardia * Cardiac arrest within the prior 6 months * New York Heart Association (NYHA) class III or IV heart failure * Pulmonary arterial hypertension treated with inhaled or intravenous pulmonary hypertension-specific therapy * Ejection fraction \<40% * Determined to be unsafe for participation in this program as assessed by a clinical nurse or investigative team.