Serious Giving Blood

So, I'm gonna give blood again tomorrow.Honestly though, I hate needles. A lot. I have a high chance of passing out as well, but I know people that have had to have blood transfusions to stay alive. And it's honestly a really cool thing to do. I've had people actually respect me a bit more and it's a cool experience in general.

So I was curious. Who here has ever given blood/needed blood. What experiences, good and bad, have you had with it.