I don't like them, but if I have to have them then I've got no problem. Vaccinations and so on I'm fine with, I just try not to think about the fact that a long sharp object is poking through my arm. I won't give blood though. I'm a registered organ donor, but I won't give blood or bone marrow, because I'm too nervous about needles going straight into a vein or my bone (apparently donating bone marrow really hurts, though I'm not sure myself).