Researchers have been studying the health benefits of laughter for years. In 1995, Dr. Madan Kataria of India and the creator of Laughter Yoga, was studying laughter for its' health benefits. He gathered a few people together in a local park and asked them to share jokes. It only took a couple of weeks for him to discover humor is different things for different people and the joke telling was not working. I know I have seen/read/heard things that people find extremely funny, and I don't, and visa versa. Everyone's sense of humor can be very different.
Dr. Kataria discussed the joke-telling problem with his wife, Madhuri, a yoga teacher. She suggested that laughter did not have to be real to be beneficial to one's health. Laughter could also be faked and be beneficial. The result? The creation of Laughter Yoga!
Laughter Yoga combines laughing exercises with yoga breathing and any number of people can participate. The exercises may start with fake laughter (fake it 'til you make it) but often end with good solid laughter! Sample Laughter Yoga sessions can be found at Sample Sessions.