Sometimes we don't know what someone is really thinking or how much they're truly hurting. It's a very profound realization. Sometimes you don't know who has eaten that day, or who won't. Perhaps what they're going through while all along they're smiling and pretending their life is okay. If you just stop and try to think what the other person is feeling, it's possible we could all live peacefully. But it's truly a hard notion for people to comprehend.
You see smiling people walking down the hallway everyday and they could turn out to be psycho-murderers. Maybe this smile hides a girl who cuts herself at night, because you tell her she's not good enough each and everyday and maybe, just maybe, it hid the pain carried by the little boy who hung himself because he was gay. So yeah, smiles are pretty damn scary, if you care about others.
Inner peace begins the moment you take a deep breath and choose not to allow another person or event to control your emotions. -- read: http://www.marcandangel.com/2015/06/28/7-little-habits-that-stole-your-happiness-yesterday/