I've always had low blood pressure. I almost didn't get into the Marines in 1996 because of it. The medic at MEPS had to take several readings until he got one that passed... heh.
Today I tried to donate blood at the Red Cross, and I couldn't because my heart rate was too high (from walking there). But they also said my bp was pretty low, 92/60.
As far as I can tell, I suffer no ill effects from having such a low bp. I'm lean (182cm, 75kg) and physically active. Should I be worried about it? Are there any dangerous conditions that could be causing it?