Smile is from the heart, and your happiness, sadness and happiness are all on your face. You have to ask yourself first, are you happy? Why are you happy? In fact, there are many smiles when you exercise smiling, such as smiling in front of the mirror and insisting on smiling at yourself every morning. Try to mediate feelings and make more friends. Look at those children, their innocence, their smiles, how sincere. Why can't we do it?