Truth be told, I didn't know why I wanted to help donate blood until I thought of it being a generous way of saving lives. I find it great to be of help and not wanting anything in return.
I have a sister and she had a condition causing her was losing lots of blood due to feminine issues. I wasn't aware at the time until after I donated blood. She had to have a blood transfusion and she is doing just fine. Wow, I donated blood to save a life, and my sister's life was saved as well. It's truly a blessing.