A smile costs nothing but gives much. It enriches those who receive without making poorer those who give. It takes but a moment, but the memory of it sometimes lasts forever. None is so rich or mighty that he cannot get along without it and none is so poor that he cannot be made rich by it. Yet a smile cannot be bought, begged, borrowed, or stolen, for it is something that is of no value to anyone until it is given away. Some people are too tired to give you a smile. Give them one of yours, as none needs a smile so much as he who has no more to give.
Peacefulness is an inner sense of calm - it comes from becoming still - in order to reflect and meditate on our inner wisdom and receive answers. A peaceful heart is one that is free from worry and trouble. It's becoming quiet so we can look at things quietly so we can more clearly understand them and thus come up with creative solutions. It is learning to live in the present.
It takes a lot of work from the face to let out a smile, but just think what good smiling can bring to the most important muscle of the body... the heart.