When you live in a big city among all these busy, worried people, it's very gratifying just to find a consistently cheerful person. Someone who smiles at you, makes eye contact, doesn't mind getting your attention just to say hello. Maybe it only works if it's more than surface-level cheer -- maybe you come across as blustery and false if you just put on a happy face -- but some people really do have a daily healing effect on the rest of us just by walking around and creating an impression that things are pretty much okay.
