We should all smile more often, in general. Just the simple act of smiling or laughing can make you happier.
But even better: smile at a stranger. Too often we brush past strangers without a glance, or a straight or scowling face. At best, we might give people a tolerant little smile, to show that we are not mean. Usually most of us try to avoid any eye contact at all.
Try this instead: look strangers in the eye, and give them a genuine smile. In most cases, you’ll get a smile in return. The more you smile, the more smiles you’ll see in return.
End result? A happier world. So simple!