21 observations from people watching 

6. It is easy to tell how happy someone is to see another person enter a conversation. There is happy, and there is polite, and they look very different. Polite has a mechanical quality to it, like carrying out all the right movements to replace batteries in a remote. Happy has a boundless quality: unpredictable, even when it is at a low level. There is an openness, allowing another person to surprise and delight them. The easiest way to say this: there is no script for happy. It tumbles out of the body. Polite comes from the mind –it is restrained and calculated – measured lines and pauses. There are reinforcing loops in a polite person and a happy person. A person closed to the possibility of delight finds less of it. A person open to it finds more.

#9, #15 are other favorites.