I just took my blood pressure. What is going on?!??!?

I am an overweight 20 year old woman. 5 foot 6.5 inches. 150 pounds. Very small frame. I just got back from a run and I took my blood pressure on my dad's machine. He has high blood pressure so I figured mine would be through the roof after doing strenuous physical activity. I got 75 SYS mmHg, 52 DIA mmHg, and 57 Pulse. Why was it so low? Does this mean I should be increasing my activity?