I had major surgery in 2009 when I was 39. I had lost a lot of blood and was extremely anemic. My hemoglobin was 4 (about 1/4th normal levels). One doctor said he was "terrified" to operate on me without blood. I was hospitalized for a month before it to try to build it up a little bit and figure out a plan.
The way it works, you explain your stand to every nurse and doctor before the surgery, then the morning of, you get rolled down, and you're sitting in your bed waiting to be wheeled in to the operating room, and people are coming into work - doctors, nurses, receptionists, blood takers, cafeteria workers - they're all talking about their weekend, or some other chatter, and you're freaking out because you're about to be cut open, and worried about dying. It's surreal!
Then they come up to you, one by one - each doctor, nurse, anestesiologist that's about to take part and they each make you sign that that's what you really want - no blood.
For me, the last one was a second anestesiologist, who asked me if I realized what it meant to be brain dead, what a burden to my family that would be! Am I sure that's what I want? And he told me he used to work at a Witness Hospital where a lot of witnesses, when they found out what that meant, secretly gave him permission to administer blood.
It was like Satan himself standing there before me at my moment of temptation. Thankfully I passed my test. And I'm sure that he made up his story about "all those witnesses" too, but at the time, it seemed believable.
There's a lot more that happened before and after that too. Very scary, because I have three little girls. Since then, I've concentrated on building myself up in any areas that I didn't fully understand, or where I had any doubt. I feel that was a major test for me, and prepared me for anything at all that may come in the future.