- Feels better. When you pull your muscles into a smile, your face sends feedback to the brain that modifies how your brain processes emotional content. The end result: You feel better when you smile. Some research suggests that smiling even feels better to your brain than eating chocolate (you may wish to test this out at home).
- Doesn't look grim or bored: When your face is at rest, your physiology works against you, since most people's mouths are either a flat line or slightly downturned. Even a small smile will counteract that appearance. (A quick look at people on television who don't think the camera is on them will show you those flatlines or downward turns of the mouth, if you need proof).
- Can hide what she's thinking: A benign smile is a great safe mask to wear, particularly when you're speaking in a tough negotiation. What is she thinking? they'll wonder. Make like the Mona Lisa to keep your face from belying your feelings, whether you're angry, nervous or feeling not-so-confident. Smiling's the best fake-it-until-you-make-it trick I know.
- Is more engaging and impressive to watch: How the audience perceives you is a big part of public speaking success. Some studies show a beneficial boost in perception of the speaker who smiles--specifically, smiling makes you look courteous, likeable and competent.
- Will look better in pictures or on video: If you've ever winced when you saw video or photos of yourself speaking because you looked grim or angry, confused or sad, just smile. It's especially good to keep a smile going when you're listening (say, during the Q&A portion of your talk). Make it your default "at rest" expression.
- Will get more positive feedback from the audience, because research shows "it's difficult for us to frown when looking at someone who's smiling." Smiling is "evolutionarily contagious," Gutman says.
- Feels less stressed while speaking: Smiling lowers your blood pressure, increases the mood-boosting hormone endorphin (think runner's high), and reduces the hormones that enhance your stress, like cortisol, adrenaline and dopamine. I coach speakers to start smiling 10 minutes before their talks for just this reason.
This post also appeared on Ragan.com, and was selected by Six Minutes blog as one of this week's top public speaking blog posts.