Not everyone need to know the burdens you carry upon your heart. That smile, hope and strength is what pulls you through another day, knowing you are not alone but, carried by God himself as promised.
~ Dianesandy Mark
It also takes less muscles to smile than frown so why not do less work and smile!
When you smile, is because you are reflecting your inner and the inner is the perfection of your life. Keep smiling to understand the perfection.
Nobody is perfect, a smile brings a sense of friendliness, although one does not in its best self at that time, keeping troubles or stress at heart.