How often do you smile at people?

Two months ago, I had to be at a friend’s house and was in a rush to get there. I was stressed from work, so knackered and it was just one of those days where you wake up on the wrong side of the bed. So I hopped on the bus, greeted the bus driver and then… he gave me the most genuine smile I’ve ever seen. His smile was so infectious! He didn’t give me the “fake” or “social” smile. I could tell it was his true smile. I don’t even know why he was smiling to me but he fucking made my day. From a shitty day, I ended up having a joyful day.

I’m just a bit curious as how often do you smile at people and why?