What a wonderful universal language this is! Smile and you can diffuse all the tension. Smile and you can win hearts. Smile and the audience will remember what you said while you were smiling.
Have you ever thought that we have such a simple yet highly powerful tool in the form of a smile? When I take my son out (he is 15 months young) he smiles at so many people. These are strangers in different places – parks, malls, museums – and they mostly smile back. His smile is infectious. I am sure they would remember that smile for some time.
Public Speaking is about connecting with your audience. Smiling brings positive energy to your speech. From a psychology perspective, when you are saying an important point make sure you give a smile, even a hint of a smile, and your audience will remember that point for a long time.
So, with all the great benefits of a smile, start that practice right now! Are you smiling?! :)