text: This is how it works It's all about those muscular action units. They even indicate the difference between a genuine smlie and a forced one. In the real smile, the zygomatic major (muscles taht begin at your cheek bones) lift the corner of your mouth. (That's our instruction #1.) Muscles are called orbicularis oculi pars palpabraeus make crow's-feet around your eyes.(That's instruction #2.)