smile is a warm-hearting expression,so,it should come from the bottom of your own heart.always remind yourself that your smile should be sincere and friendly.only in this way,can it be a charming symbol shown on your face.
smile also means gratefulness.a person cannot smile without a grateful heart.
from the moment on,be grateful to the world,be grateful to the ones around you,and be grateful to the things you have.then you will smile.a true and beautiful you is shown before everyone.