What's more, she suggests, we could all be doing our bit for the country by beaming at each other. None are so rich they can get along without it, and none so poor but are richer for its benefits.
Smiling makes you more creative. People who are constantly smiling appear to be more trustful than those who are not.
The added oxygen from smiling and laughing benefits your body while improving your immune system. A smile is an inexpensive way to improve your looks.
It happens in a flash and the memory of it sometimes lasts forever.
People who smile are more productive. In the study, 36 volunteers were asked to play a gambling game against a computer animation which would either smile politely - with the mouth only - or 'genuinely', with crinkle lines around the eyes too.