Laughter can add minutes and hours and days to your life. As children, we laugh many times every day. As adults, not so much. In India people beleive if you laugh everyday it will keep diseases away.
Laughter yoga is a great way to get your laughter in. According to the main laughter yoga website:
Laughter lowers the level of stress hormones (epinephrine, cortisol, etc) in the blood. It fosters a positive and hopeful attitude. It is less likely for a person to succumb to stress and feelings of depression and helplessness, if one is able to laugh away the troubles.