I tend to smile at strangers in the street, or whatever path I may be taking to get to a location. I think that when you smile at someone, it tends to cheer up people. I think it is very difficult to be smiled at and not smile back. I am not saying everyone has to smile when smiled at, or necessarily has to feel happier, but usually for a second it brightens the day. Also, it is much better than scowling at people, and usually for me if I am having a bad day, walking down the street or hallway smiling and saying hi to people tends to help brighten me up. I always feel happier when I get a smile back.
Some people bring up the point that when you do smile at someone, it tends to give them the idea that you want to talk to them. I realize that does happen. It happens to me often enough to know that it does, but I think when you do get into those talks, it never has to be anything long and drawn out. For me, if I get into one of those talks, and I really do not want to talk that long, I usually just say a greeting like "Good Morning!" or "Mornin'" if I don't feel like saying two words. I might comment on the day, like it is nice out or something. I never think talking at all has to be long, and usually it is not. If you don't want to talk at all, I suppose you can look down, or not smile, but I think smiling and saying hi to people can help wake you up if you are feeling sleepy, or brighten your day if you are down in the dumps.
In the end though, I just find smiling at people down the street helps brighten up everyone?s mood, even if it is on a small scale. Smiling is a contagious thing, and when you keep smiling everyone starts to smile. For all you know, you might have cheered someone up, and made someone?s day. You might have even turned someone who was about to do something horrible away by making them feel better about themselves. You never know.