The first time I heard about the health benefits of laughing was at a health seminar. The story went like this:
A man heard from his doctor that further treatment of his cancer was of no use and that his life prospects were about 3 months. He had a lot of money and no heirs, so he decided to spend his last days as pleasant as possible.
He took up residence in a penthouse of a hotel with full board and access to the Humor Channel and watched funny movies and stand up comedians all day long.
After 3 months he was still alive. And also the next 3 months passed by without anything of importance happening. So he ran out of money, was kindly asked to pay the bill or else to leave the hotel, and returned to the hospital for a check-up.
His cancer was gone.