In 2001, just as his first child was about to be born, actor Mark Ruffalo (known for his portrayal of Bruce Banner/The Hulk in the movie The Avengers) discovered he had a brain tumor. It turned out to be benign, but half of his face was paralyzed for a long, uncertain year. The paralysis went away in time, but his left ear's hearing vanished forever.

"You start making deals," said Ruffalo, "OK, whoever, whatever—take my hearing, but don't take me away from my kid. That's a heavy moment to happen at three-year-old. But it was a blessing in disguise. I got a lesson in fallibility and mortality, you know, 10 years, 15 years ahead of my peers."