It has been said that you can tell a lot about a person by the way they treat people who have no power over them. What can the waitress or cashier tell about you? Is it consistent with how you act at church or among your friends? Is it in keeping with what you are teaching your children? Is it the way you would want to be treated if you were in their place?
They are people with feelings too, a smile and friendly gesture from you could be a huge blessing to them. So go ahead, and make their day.
Take Away: Is it the way you would want to be treated if you were in their place?