Citations: Smile (thinkexist.com)

“If a man smiles all the time, he's probably selling something that doesn't work”
“One who smiles rather than rages is always the stronger”
“Smiling makes you feel better about yourself, even if you don't feel like it. And it always makes other people think better of you.”
“Smile! It's irritates people.”
''Smile when it hurts the most''.