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.