I am a blood donor. Not as prolific as my father. My Pop was O Negative and they would track him down to donate ever 56 days. No telling how many gallons her donated in his lifetime.
My blood type is much more mundane, good ol' A Positive. I manage organizing my employer's blood drives with the Red Cross. We have one per quarter at three separate sites where I live and work. We collect about 600 pints a year or so.
I am an irregular apheresis donor, too. There was a time when I went almost every two weeks, but after a while my arms hurt more and more from the frequent donations so I toned back. Then I stopped. I went this Saturday morning for the first time in over a year. It is a significant time commitment, about 2 - 2 1/2 hours. Other than the needle sticks, it is generally an easy process. They have a decent selection of DVDs to watch while one is in the chair.
I opted out of the movies on this visit and listened to podcasts. That turned out to be a bad call, as I kept drifting off to sleep. It is kind of comfy in the chair, heating pad on my lower back and covered in a think cotton blanket. It can be a chilly process, as they keep the room fairly cold and the blood cools a little as they run it through their machine to extract the platelets and pump the remainder back into the other arm.
I enjoy donating for another reason. A member of my immediate family and a member of my extended family require regular platelet donations. It is not feasible for me to travel where they live to donate, nor is it cost effective for the Red Cross to ship my donation to them. But someone in their areas are going to the effort to donate for them, so this is my way of giving back to those that help keep them alive. It seems the least that I can do.
A fair number of people cannot donate do the exclusions that limit donors. Other people cannot handle the process of donating and pass out. I used to be that person, and to this day I cannot watch the needle stick or look at my arms at the needles and tubes without getting woozy, and I have been donating for over 25 years. But if you can donate, and find the time, it is appreciated by the people that need whole blood or platelets.