In 1964, the journalist Norman Cousins took a really stressful trip to Russia. Work was wearing on him, and on top of that, his surroundings were pretty unhealthy, exposing him to dangerous fumes like diesel exhaust. Those factors, doctors believed, came together to cause the grave illness that overtook him soon after: ankylosing spondylitis, a degenerative spinal disease with a grim prognosis. Cousins was told he had a 1/500^th chance of survival. Over time, he would lose all physical mobility.

Stress, combined with a weakened immune system, had caused this horrible condition, doctors said. Well, if that's true, then the opposite of stress should heal it, Cousins reasoned. And so he set about creating positive emotions that would boost his immune system.

Cousins checked himself into a hotel, where he pumped himself with vitamin C and embarked on an experimental form of therapy: laughter. He watched Marx brothers movies, read humorous books, and focused his mind on all things funny....