Here are some posters put up around college to inform viewers of how some smiles work and to encourage them to smile more. The bottom left poster was just a collection of smiles dotted about the paper which on its own doesnt make much sense but when seen in the context of the other posters you can soon put two and two together. I found it pleasing to see that a few hours after the poster was put up, someone had doodled some more smiles onto the poster. Hopefully it'll stay up there for a while and the poster will be covered in them.

Smiles are good for you and everyone around you. Not only do they make you appear more friendly, approachable and happy but they can make you live longer. Here's the scientific bit;
When you smile, your body releases endorphins, natural painkillers and serotonin. This process can boost your immune system and help to reduce ulcers, headaches, backaches, high blood pressure, mental problems, asthma and fatigue. So smile like you mean it :).

A smile is formed by a combination of the contractions of either or both the Zygomatic Major Muscles and the Orbicularis Oculi Muscles. This can be a voluntary or involuntary action but generally, a true, involuntary smile occurs when the Orbicularis Oculis are contracted.