From AARP (38+ million members in the USA in the 55+ age group): Laughter Can Be as Good as Exercise for the Brain. “Laughing is a simple thing that anyone can do,” says Gulshan Sethi, a cardiothoracic surgeon at the Tucson Medical Center. “You don’t have to take any medicine. There are no adverse side effects. You have nothing to lose.” See https://goo.gl/vNu1hg