According to this excerpt from Louis R. Franzini's book, Just Kidding: Using Humor Effectively, laughter just may actually be the best medicine.
Steve Wilson, an Ohio psychologist and self-proclaimed "joyologist," launched the World Laughter organization in 1998 after meeting Indian gurus who were advocating laughter...as a road toward health and peace....
Laughter clubs are organized by trained and certified laughter leaders anywhere for any sized group that can meet one or more times. What is unusual is that the group participates in a variety of laughter exercises for which there is no humor stimulus. The participants laugh loudly as a group, simply upon instruction to use different laughter sounds and cadences. They, and any observers who may come along (if the group has gathered in a public place such as poolside or the lobby of a hotel), just laugh heartily. Capitalizing on the laughter contagion effect, soon everyone within earshot is also laughing.
It is an amazing phenomenon. People in a dire or sober mood, who are preoccupied with their own personal problems, who fear for their business's success or the nation's future or a family member's illness or whatever issue is on their mind, all temporarily forget those stressors and laugh along with everyone present, friends or strangers. All are laughing and all quickly feel good. It's simple, it's bonding, it's stress reducing, it's physically relaxing, it's free, and it's legal!
Truth is...according to Proverbs 17:22, "a cheerful heart is good medicine." According to laughter clubs, it's good even if you have to fake it till you make it.