"She's a very charming and delightful creature," quoth Mr. Robert Sawyer, in reply; "and has only one fault that I know of, Ben. It happens, unfortunately, that that single blemish is a want of taste. She don't like me."
If you have only one smile in you, give it to the people you love. Don't be surly at home, then go out in the street and start grinning 'Good morning' at total strangers.