The sound of roaring laughter is far more contagious than any cough, sniffle, or sneeze. When laughter is shared, it binds people together and increases happiness. Laughter also triggers healthy physical changes in the body. Humor and laughter strengthen your immune system, boost your energy, diminish pain, and protect you from the damaging effects of stress. Best of all, this priceless medicine is fun, free, and easy to use.