When was the last time we initiated a smile? Doing so could be awkward at times especially if the other party is a stranger, and not all strangers are necessarily friendly.
But think about it, what percentage will reciprocate? Perhaps 99%, even in an unpleasant setting e.g. a hospital waiting room. Smiles are known to be contagious, and a person has to make a conscious effort to not return our smile. And a simple smile can reduce anxiety and change our mood and that of the person who acknowledges our smile. So why not wear a smile often and offer a friendly smile to people we cross path with.
Peace begins with a smile.