Is laughter really the best medicine?

Today, a person I communicate briefly with made me LOL to the point hours later I am still laughing; yes, she was a city employee I briefly communicate with-yes, my life may seem shallow.
But really, how important is humor to your day to day grind in providing you with happiness.
I work with lots of engineers, so it is not easy to get a laugh from anyone-they always seem to analyze the comment for authenticity before any response. So, humor in the workplace is precious and rewarding.