There was this fellow who survived the Holocaust/concentration camps who once said,
"You know why it is that I'm alive today? I was just a teenager at the time. We were on the train, in a boxcar, being taken to Auschwitz.
"Night came and it was freezing, deathly cold, in that boxcar. The Germans would leave the cars on the side of the tracks overnight, sometimes for days without any food, and of course, no blankets to keep us warm.
"Sitting next to me was this beloved elderly man from my hometown. I recognized him, but I had never seen him like this. He was shivering from head to toe, and looked terrible. So I wrapped my arms around him and began rubbing him to warm him up. I rubbed his arms, his legs, his face, his neck. I begged him to hang on.
"All night long, I kept the man warm this way. I was tired, I was freezing cold myself, my fingers were numb, but I didn't stop rubbing the heat on to this man's body. Hours and hours went by this way.
Finally, night passed, morning came, and the sun began to shine. There was some warmth in the cabin, and then I looked around the car to see some of the other Jews in the car. To my horror, all I could see were frozen bodies, and all I could hear was a deathly silence.
Nobody else in that cabin made it through the night. They died from the frost. Only two people survived: the old man and me.
The old man survived because somebody kept him warm; the teenager survived because he was warming somebody else...