First we should smile to ourselves.There are a lot of unpleasant thing in life.For example,you can't pass the exam; You have no many friends; Some people do not understand you.But in fact they do not change you at all.Smile to them.They are parts of the life.Also we should learn to have confidence.Believe you are the best in the world.
Second,we should smile to others.It can make you be friendly all the time.You will have deeper friendship with others.
In on word,smileto the world all the time,the world will smile to you.