It is just a simple selfie video of a Texas mom laughing hysterically at the talking Chewbacca mask she bought herself as a birthday present.

But when Candace Payne wrestles the mask from its box and slips it on, and then can’t contain her childlike glee at its Wookiee sounds, viewers couldn’t help but share in her genuine excitement.

That’s why the original video, posted last Thursday, has been viewed on Facebook more than 130 million times.

There’s no exact science to what makes one video go viral online among the millions posted to social media every day. But studies have shown the content that makes people feel good is what is most clicked and most shared.

Human emotion is contagious. Hearing another person’s laughter triggers the part of the brain that controls smiling, according to scientific research. It’s why sitcoms use laugh tracks. It’s why watching Payne giggle from beneath the mask made us laugh, or at least smile, too.

But it’s more than that. Payne’s video is a reminder that life is filled with simple pleasures. Even with all the negativity in the world, you can drive to Kohl’s, buy a toy for under $20 and crack yourself up alone in your car. It’s uncomplicated. It’s not stressful.

And Payne, a 37-year-old stay-at-home mom is a perfect messenger. She’s a normal person who doesn’t seem to take herself too seriously. She jokes about her weight, but not in a self-pitying way, and cares little that fellow shoppers can see her in the driver’s seat talking to herself while wearing a Chewbacca mask.

The silliness and the lightheartedness of the moment was unexpectedly captivating. And for those four minutes of video we were let in on Payne’s fun. To underscore that, many friends and strangers alike wrote on her Facebook page that she had made their day.

It also resonated on a deeper level. Payne told NPR that people have sent her private messages that they were battling depression or mourning someone’s passing. She said people wrote things like, “I hadn’t laughed since they died and this video made me laugh again.”

On Sunday night, Payne posted another live Facebook video (which had 575,000 views in its first hour) where she tells her now legions of fans that she’s currently in her “favorite city” because the next morning she’s going to be a guest on “Good Morning America.” She lets loose again that hearty, infectious, Julia Roberts-esque laugh, as she opens her hotel window to show the glittering Manhattan skyline.

“O-M-Goodness,” she says. “I can’t even tell you how excited I am.”

And somehow so are we.