There will be two primary treatment arms. Patients with PH will be randomized to either aerobic exercise training plus education (AET) or education only (Ed-only) treatments. A comparison group of patients with ILD who do not have secondary PH (ILD-only) will also undergo the AET arm. Exercise training will consist of a 10-week regimen of supervised treadmill or over ground walking three times a week. Exercise session duration will be 30 minutes and will progress to 45 minutes per session over the 10 weeks. The intensity of the exercise will be between 70 and 80% of the heart rate reserve.