At the end of “Inside Out,” the 2015 Pixar movie about the emotional life of a girl named Riley, a new button appears on the console used to control Riley’s mood. It’s emblazoned with one word: Puberty.

Joy, one of the main characters who embodies Riley’s emotions, shrugs it off.

“Things couldn’t be better!” Joy says. “After all, Riley’s 12 now. What could happen?”

The answer has finally arrived, nearly a decade later, in the sequel “Inside Out 2.” Riley is now a teenager attending a three-day hockey camp as new, more complex feelings take root in her mind.

There’s Embarrassment, a lumbering fellow who unsuccessfully attempts to hide in his hoodie; the noodle-like Ennui, who lounges listlessly on a couch; and Envy, with her wide, longing eyes.

But it is Anxiety who takes center stage, entering Riley’s mind with literal baggage (no less than six suitcases).

“OK, how can I help?” she asks. “I can take notes, get coffee, manage your calendar, walk your dog, carry your things — watch you sleep?”

A little anxiety can be helpful, experts say, but the emotion has been getting out of hand in many young people’s lives, especially in recent years. Riley’s struggle is emblematic: For Kelsey Mann, the director, the film became an opportunity to help viewers of all ages feel less alone.

“A big part of dealing with our emotions is actually naming them,” he told The New York Times in a recent interview. “And suddenly, when they get recognized and seen, the intensity starts to go down a little bit.”

In the movie, Anxiety can be … a lot. But eventually she conveys a few powerful lessons: Experiencing some anxiety is normal, our shortcomings are simply part of who we are and all of our emotional experiences are an important part of our identity.

Even the uncomfortable ones are natural and necessary, said Lisa Damour, a clinical psychologist who advised the filmmakers.

“They help keep us safe. They help to guide us,” added Dr. Damour, who has written for The Times and is the author of three books about teenagers. “You cannot prevent them or shut them down if you hope to thrive.”

It’s when Anxiety goes off the rails, kicking out Joy and the other core emotions and projecting disastrous scenarios, that Riley becomes overwhelmed.

Anxiety was always meant to be the antagonist of the film, Mr. Mann said, but in early drafts of the script, the character came across “almost like a cardboard villain.” She “wasn’t very likable. And I didn’t understand why she was doing what she was doing,” he said.

So he dug into the scientific research and spoke with Dr. Damour and Dacher Keltner, an expert on the science of emotion and a professor of psychology at the University of California, Berkeley, who also worked on the first movie. Eventually, Mr. Mann’s team decided that Anxiety was motivated by love for Riley, just like Joy was.

The final version of Anxiety is mostly endearing and sincere: She wants to help. Her job, as she sees it, is to plan for the future and protect Riley “from the scary stuff she can’t see.” As her personality took shape, the filmmakers injected Anxiety’s appearance with a bit of whimsy.

Her orange hair shoots upward like a bouquet of optical fibers that defy gravity. Eyebrows dance above her piercing eyes as her mouth stretches into a toothy grin that’s part smile, part grimace.

Anxiety aims to protect Riley at all costs by imagining every possible mistake the teenager could make. But it’s a strategy destined to fail.

The theme of perfectionism is threaded throughout the film, and it drives much of Riley’s anxiety. She’s incredibly hard on herself at times, struggling to reconcile the opposite characteristics that exist within her: She is kind and also selfish. She’s brave, but she also gets scared.

We often think of ourselves in an “either-or fashion,” Dr. Keltner said. “But we’re many things,” he added, and the film encourages teenagers to embrace that notion.

Dr. Keltner sees the movie as a call to be easier on ourselves, savor the good things and accept our complexity. Riley’s anxiety is not pathological, he said; it is an emotion that is trying to tell her something.

“Emotions have the wisdom of the ages,” he said. He hopes young people will listen to the good intentions of those emotions.

Anxiety is “something that so many kids experience, but they don’t always have a label for it,” said Elana R. Bernstein, an assistant professor at the University of Dayton School of Education and Health Sciences who was not involved in the making of the film. “I think the first piece is normalizing it.”

By acknowledging the feeling and coming up with coping strategies — identifying catastrophic thoughts or trying relaxation techniques, for example — younger children can prepare for the more complicated situations that will arise as they get older, said Dr. Bernstein, who researches strategies in schools to reduce anxiety.

In our culture, Dr. Damour noted, we’re often told that mental health is about “feeling good.” But in reality, she said, mental health is about “having feelings that fit what’s happening and then managing those feelings well.”

And that’s just what Riley must learn — that Anxiety and Joy cannot be in control at the same time. The film’s screenwriters, Meg LeFauve and Dave Holstein, found this relatable.

When she was younger, Ms. LeFauve’s father used to call her “Moody Meg.”

“I am sure it was hard to live with me!” she said in an email. “I was a bundle of swinging emotions and raging anxiety.”

She now realizes that her sensitivity stemmed “from the beauty of my intense imagination.”

“When my anxiety is on the controls too strongly, maybe I need to go find even just a breath of joy,” she said.

Anxiety is something that has both positive and negative attributes, Mr. Holstein said. And it’s an emotion that can feel more intense during puberty.

“At different points in your life, different things drive you,” he said. “Sometimes joy has to step back.”