Congenital Heart Disease Physical Activity Lifestyle Study V.2

Inclusion Criteria: * Between the ages of 15-25 years * Diagnosed with moderate or complex structural CHD * Actively receiving care from a cardiologist at Nationwide Children's Hospital (NCH) or Ohio State University (OSU) Exclusion Criteria: * Unable to speak and read proficiently in English * Have a diagnosis of a genetic syndrome that impacts multiple organ systems * Have cognitive impairments that would interfere with completing study measures * Have been engaged in a formal exercise program within the past 6 months, * Have participated in the intervention arm of the previous CHD-PAL Study * Have undergone open-heart surgery or had a valve replacement in the last 3 months * Are unable to complete an exercise stress test using a treadmill * Are pregnant * Are prohibited to engage in at least moderate levels of physical activity by their cardiologist * Engage in \>30 minutes of moderate-to-vigorous physical activity per day, on average per accelerometer * Have contraindications for exercise based on an exercise stress test (e.g., exercise-induced arrhythmias or evidence of cardiac ischemia)