Well, this wasn't as dramatic as saving someone's life, but;
I returned to my car one day last week, in the supermarket car park, to find that I had a flat tyre. I tried to pump it up with my foot pump, but I wasn't getting anywhere. Suddenly, there was a man standing next to me with one of those electric inflators in his hand. 'I don't like to see a man struggle,' he said, and offered the use of his tyre inflator, which pumped the tyre up enough to enable me to get home and change the wheel. He had seen me from the far end of the car park and immediately came to assist. Perhaps the fact that I am 74 had something to do with it, but I thought that was a kind gesture.