When you smile, it helps lift 'everything' up - even your spirits!
In Toy Story 3, Barbie complains that her cheeks hurt from all the smiling:
"Oh, my gosh, my cheeks are killing me. I can't keep smiling like this anymore."
Barbie's cheeks started 'hurting' because smiling, and other facial expressions, directly affect facial muscles.
When you practice these 'expressions' as facial exercise, it can result in a very nicely toned face.
This works rather quickly, too: unlike other muscles, facial muscles are attached directly to the skin.
...So, before trying any type of Cosmetic Surgery, give smiling a try instead!
(See more information HERE.)