This happened summer last year but I felt like sharing.

On a rather warm summer evening I was working at a train station, it was during rush hour so it was pretty hectic and I was helping a passenger find the train he was intending to get.

Out of nowhere he comment "by the way every time I come through here you have the biggest smile"

Me: "Oh really? Thank you so much! Commuting can be quite stressful so I find a cheery face can do a world of good!"

"You keep it up man, take care!"

I was quite taken aback, I've had a few compliments on my announcements and helpfulness before but the fact he took the time to comment on that really made my day :)