The approach people suggest you is good. It presupposes a kind of adaptation to the unpleasant experience. Another approach is analytic one. Try to think about your past experience, may be of a very far in time past experience, and remember the moments when you were really scared by something. It might not be blood, but something red, which scared you. It could also be some other unpleasant experience against red background etc. As soon as you remember and realize, that is bring to your mind, your unpleasant past experience, it will be easier with your present fear and in the long run the fear will disappear at all.