I believe singing would also have a positive effect, especially if you sing "The Laughing Song" <img src="i/expressions/face-icon-small-wink.gif" border="0">
One thing that clicks between me and my wife is how I can make her laugh, and myself as well. Many of those incidents turned into unregrettable coughing fits, though.
So, I agree that laughter is even good medicine for the lungs.