Little drops of water, flowing into the same direction creates a vast river. A little change in public opinion grows massive and outcasts the president of the country (just happened in Arabic Spring in Egypt). A man, who commits little crimes every day, becomes a fierce criminal ending up in the gallows. A little practice of good habits every day, leads to a happy life.
So, little things matter. Never underestimate the power of them. When accumulated, they can be greater or worse.
So, smile with the man next to you, help a man in need, assist the poor, help a kid, who is good at learning, plant a tree, smile with the lady sweeping the floor in your office, give the way to a stranger in the street, kiss your wife every day, say your kids every day that you love them so much, help your wife in cooking, give a hand to your mother at home. They will love to be around you. Respect you. You also be so happy and satisfied with your little acts of kindness.
Do one little good thing every day. It will come to you in thousand-fold. You will feel great. Starting from you, the entire world will change.