Mimicking a smile and experiencing it physically help us understand whether our smile is fake or real, so we can understand the emotional state of the smiler.

to start smiling upon you.

You smile all the time.

Smilin' up at you

And, unlike lots of chocolate, lots of smiling can actually make you healthier.

Smile. Smile. Open the mouths.

The professor smiled slightly.

Is that a mocking smile or a tender smile?

Come on with the rain I've a smile on my face

You smile and when she asks you what you want you answer

That's the smile I use that's his smile.

Where's that famous smile?

Wipe that smile off your face.

Okay, so you smile, frowning.

If you smile, I'll be happy.

Everything's there but the smile. I leave that to you.

You smile when your picture's taken for the newspaper.

Madam prefers when you smile.

So it sees a smile as a smile.

Smile.

A tender smile.

Smile, please.

A recent study at Penn State University found that when you smile, you don't only appear to be more likable and courteous, but you actually appear to be more competent.

But always with a smile, always with an enthusiasm, that is incredible.

You're so handsome when you smile.

What you get out of that is not smiley ness.

Yet you smiled at him. Why?

Even tried to smile at me didn't you, my dear?

You can see it a mile off.

The professor grinned.

The professor smiled a little.

Smiley

Smile.

Good. A little smile.

Keep on smiling.

Brace up. Smile!

Your Grace, smile!

So, what'll it be Pfeiffer?

But your smile will cure him. Come.

Smile, friendly.

Mike smiled.

I tried to smile.

So they've been seen together and he smiled at her.

That the Blessed Virgin had smiled

And the way you sashay down the street, smiling' when we meet.