Research
Studies have found that laughter releases bad and distressful emotions that cause harmful chemical effects on the body. They found that laughter activates the T cells, B cells, immunoglobulins, and NK cells; it helps to fight viruses, and regulate cell growth. This could be very important in the research for cancer since it also fights against tumorous cells.


A person's heart can reach up to 120 beats per minute (bpm) when laughing. Laughing can lower your blood pressure, increase vascular flow, and boost the immune system. It gives the diaphragm, abdominal, intercostal, respiratory accessory, and facial muscles a complete workout. Some people, depending on how they laugh, may even use their arm, leg, and back muscles when laughing.

Studies have found that laughter also releases endorphins in the brain; are our bodies' natural pain killing opiates.

Another study found that exposing schizophrenic patients with humor reduced their aggressive behavior, depression, and anxiety.

Laughing wards are being added to numerous hospitals these days.

Laughing clubs that started in India have been so successful that they have spread throughout the world.

Quotes
Charak Samhita (Ayurveda's main text) says that the cause of health is happiness and the cause of disease is unhappiness.
 
Nearly 2000 years ago, the physician Galen stated that cheerful women were less likely to get cancer than those women who were depressed (Simonton 1978).

John Steinbeck once said "A sad soul can kill you quicker, far quicker, than a germ."

Norman Cousins started the modern laughter-for-health awareness found that watching Marx Brothers comedy films and reading humorous books removed his pain within days- a pain that doctors couldn't treat.

Dr. Patch Adams dresses as a clown at his Gesundheit Institute (hospital). To work at his hospital you must ". . .look funny and . . . be funny."
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Jokes
So here are some jokes; hopefully they will make you laugh.

A man said to his doctor,
'Everytime I drink my morning chai (tea) my right eye hurts'
doctor said,
'Take the spoon out of your cup.'

Doctor: 'Sir, you only have 6 months to live'
Patient: 'I cannot afford to pay you'
Doctor: 'OK, you have 1 year to live'

"I spent three years in college taking medicine."
"Are you well now?"

A snail was lying on its side when another snail came along. Helping the first snail upright the second snail asked,
'What happend to you?'
The snail, now uprighted, said,
'A turtle came by and knocked me over.'
'Did you see who it was?'
'No, it happend so fast'

Some tourists in India was walking through the valley when came upon a man sitting under a tree with his cow. They asked him if he knew what time it was. The man put his hands on the cows udder and said,
'Two thirty'.
The tourists thought they found a miracle saint. Awestruck they said,
'Sir, we have a dairy farm in the US. Can you teach us how to tell the time by feeling a cow's udder?'
The man said,
'I lifted the udder so I could see the clock tower in the village'

Teacher: Johnny, why are you doing your maths sums on the floor?
Student : You told me to do it without using tables!

Teacher: George, go to the map and find North America.
George: Here it is!
Teacher: Correct. Now, class, who discovered America?
Class: George!

"Why did you park your car here?"
"The sign says: 'Fine for parking!'"


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Read more details and research at:
http://fly.hiwaay.net/~garson/laughter.htm
http://www.holistic-online.com/Humor_Therapy/humor_therapy.htm

http://www.geocities.com/jokesindia/