The more C-V intensive exercise you get, the lower your blood pressure goes (down to some theoretical limit). At one time, when I was doing construction labor, the Red Cross wouldn't take my blood donation because my diastolic BP was too low to measure.
Exercising regularly for 30 minutes a day can also lower your blood pressure as it stimulates a substance in our bodies called nitric oxide. Nitric oxide helps to keep our blood vessels open. During the early stages of arteriosclerosis (or plaque build-up), one of the first things to be seen is a reduction in the amount of nitric oxide in the blood vessels. When you exercise, the accelerated pumping of the heart forces more blood to flow through the vessels. As this blood pushes its way along the lining of the vessels, more nitric oxide is released.