The best place to prove this theory is in a grocery store. For most people, the minute they walk through those automatic swinging doors and select their cart, they're in game mode. You can see it in their eyes. They’re planning how they're going to navigate the course. Thinking about how to handle blocks and interferences. Rubbing on the hand sanitizer. You know who they are. We've all seen the look. But, do me a favor. Next time you're shopping and see someone in full game mode, just smile. It startles them at first, but do not back down. An instinctual attempt to evade contact will be made, but soon their lips will twitch up and you can tell that they are grateful for the gift.
So, give a stranger a smile today. It might be the only sunshine they receive. And, if the altruistic benefits of a smile do not appeal to you, smile anyway. It can subtract the years faster than an injection of Botox.