Inclusion Criteria:

• * Diagnosis of group 1 Pulmonary Atrial Hypertension (PAH) diagnosed during right heart catheterization (RHC) according to WHO criteria 28
• * WHO functional class II to III
• * Stable clinical condition, with no change in medical therapy for pulmonary arterial hypertension (PAH) for at least 3 months before enrollment
• * Planned follow-up at University of Michigan Hospital Centers over at least 1 year
• * If enrolled in clinical trial, must be in open-label extension stage on stable medications for at least 3 months.
• * Competent to give informed consent
• * Have computer and internet access

Exclusion Criteria:

• * Life expectancy under 1 year
• * Co-morbidities which limit physical activity to a severe degree (i.e., permanently wheelchair bound, musculoskeletal disorders, recent myocardial infarction, unstable arrhythmia)
• * Current substance abuse, and/or a severe psychiatric disorder (including severe depression, psychosis, or dementia) which limits the patient's ability to follow the study protocol
• * Recently completed (\<6 months), current enrollment or planned enrollment in pulmonary rehab.
• * ≥30 minutes of exercise, ≥ 1 day per week for the previous 3 months
• * Six-minute walk distance \<150 meters or \>550 meters
• * Moderate or severe obstructive lung disease forced expiratory volume/forced vital capacity (FEV1/FVC) \< 70% and FEV1 \< 65% of predicted value after bronchodilator administration).
• * Moderate or severe restrictive lung disease (total lung capacity \< 60% predicted value).
• * Arterial oxygen saturation (SpO2) \<88% during 6-minute walk test on baseline home oxygen prescription if applicable or SpO2 \<80% if uncorrected shunt.
• * History of exercise-induced syncope or arrhythmias.
• * Pregnancy or lactation
• * Non-English speaking