I don't do this, everybody has there own issues or carry themselves in there own way, telling them to smile isn't going to make anything better. I remember a few years back I walked into a local pizza spot I go to often, and the girl behind the counter told me to smile, which pissed me because my mom had passed earlier in the summer and I had been depressed.I mean of course she didn't know that, but I don't wanna end up feeling self conscious of how I look, and irritated because someone tried to tell me what to do, on top of feeling depressed. that situation just made me even more mindful of not to say that to others.