Loss of blood

Well, I did´t really figure it out why I felt so fatigue until the end of my second lap around Voldsløkka tonight. I should have guessed earlier. I just thought it was strange to be so tired and exhausted. First I thought it was the heat (25 degrees), but then it hit me: This morning I went to give a away 450 ml of blood at the hospital (in Norwegian: "The blood bank")! No wonder my body can feel the loss. I think the human body has around 5-6 litres of blood, so almost half a litre is quite a lot, actually. You figure it out! (the percentage I mean)