I saw the hero on TV -- middle-aged or older, and a skinny guy. They showed the mark on his knit hat where the subway cars had come in contact with it. Miraculously they missed his head.

No, I couldn't have done what he did. I would wish that I could have, but even if I could move that fast (which I can't), I'm too fat and buxom to have laid flat on top of the man who fell on the tracks. I would have been flayed by the subway cars.

The guy can thank his lucky stars that both he and his rescue-ee are thin enough that they lived through the incident!