I love to smile; it is my gift to the world.

A stranger smiled at you sometime in the last month and you have no idea who they were, and it worked anyway. The mood shifted a degree and you never traced the cause.

You are doing this to people constantly in the other direction too. Most faces in public are set to neutral verging on grim, so a genuine one is unusual enough to register.

It also runs backward. Arranging the face shifts the mood a little, not only the other way around.

Cheapest thing you will give anyone today, and they do not even need to know your name.