You never know who might need your help.
I've always thought donating blood is such a small sacrifice to make to help someone in need, and is more personal and valuable than a cheque. I have given blood 100 times so far but I had to stop once I began taking blood pressure medication. For now I just give a cheque instead. I have always hoped that no one I knew would ever need the blood I and others gave, and for much of my life that was fortunately the case. But when my Dad fell ill with bladder cancer he required a number of blood transfusions to restore his strength. That blood bought our family some precious time with him. He refused them once it became apparent that he would not recover. He did not want to see such a valuable resource wasted on him. While it clearly was not, at least I was able to reassure him that I had given far more blood then he had used, so we were net givers as a family.