yoga - a Hindu philosophy that teaches a person to experience inner peace by controlling the body and mind (Webster-Mirriam dictionary entry)
Notice the dictionary entry above does not say "exercise" or "pretzel". Yoga in our society is often synonymous with the physical exercise part of yoga. However, all yoga is not the same. For example, Karma yoga is the act of service to others.
Laughter Yoga is prolonged voluntary laughter. This provides the same physical and mental benefits as real, spontaneous laughter. It is done in groups, using eye contact and childlike playfulness between participants. Fake laughter soon turns into real and very contagious laughter. There is no humor or comedy involved. Laughter exercises are done in which participants fake laughter in a particular scenario. Many of the exercises are interactive with one another. These laughter exercises as well as yogic breathing exercises interspersed throughout bring more oxygen to the body and brain, and boost happiness. Studies have shown great benefit to cardiovascular and mental health. Stretching, chanting, clapping and gentle body movement are all utilized in the class. This is followed by a laughter meditation and guided relaxation.
You can see what a laughter yoga class looks like here: https://www.youtube.com/watch?v=lGNOF8DVIPQ
So the next time you consider trying a laughter yoga class, don't think you need to be flexible or physically fit to join in. And if you feel silly fake laughing, just remember, everyone else in the room is doing it too, and by the end you will have had so much fun!