I come from a family which has always donated blood. I have memories as a child of coming in for breakfast and finding my father wasn't there. He had one of the less common blood groups and had been called in during the night to donate blood to a newborn 'blue baby'. Like him I was a donor here in Australia until my health deteriorated and I was no longer able to donate.
Eventually I ended up on the opposite side of blood donation when I haemorrhaged when giving birth and needed a blood transfusion. It just proves the point that you never know when something might go wrong and, as a recipient, I am grateful to those who had generously donated.
Donating blood is a safe, simple and relatively painless process - no worse than a blood test really - and I'd urge everyone who is fit enough to consider doing it. You will be helping others and, who knows, but you might need blood yourself one day.