You are right, smiling is really important and it makes us more positive. Especially we have to smile when talking with people to let them feel better and comfortable. The fact that I know about smiling is that we have even to smile when we talk by phone, even though the other side feels that. ☺
They definitely feel it on the other side. I have seen people that use the phone a lot keep a mirror on their desk to make sure they are smiling. Thanks @clixmoney!