If you get holes punched in your body, blood will come out. On rare
occasions, the contents of your intestines may come out, too, but do not
worry about that because someone will clean it up. But most of the time
blood is going to come out. How much? Well, your body holds approximately
one and a half gallons of blood, and you can lose 30 percent, approximately
a half gallon, without losing your hydraulics. To see what that much
blood looks like, take a half gallon of strawberry milk and pour it on the
ground. Yes, it is a large puddle, but tell yourself that that is the
volume of blood you can lose and still fight. Erase all doubt that you can
keep going and keep fighting. Know that if you stop before you lose that
much blood, it is your will that failed, not your body. Lt. Col. Dave
Grossman, On Combat
http://tipyomi-sender.appspot.com/showtip/Sheepdog%20Tip%20of%20the%20Day/During%20Combat/3