Ken Jeong imparted some advice to his younger “Wonder Park” co-stars while filming the animated adventure.

“It sounds cliché, but the older I get, I still maintain a spirit of fun on set and at work. It’s just like any job, when you get there that day — just have fun. It actually matters,” he told Variety at the film’s premiere in Los Angeles on Sunday.

“Wonder Park” follows a young girl named June (voiced by Brianna Denski) who spent her childhood dreaming up a fantastical amusement park with zany rides and talking animals. After experiencing hardships and losing her creative spark growing up, she discovers the park actually exists just as she needs it most. Twelve-year-old Sofia Mali lends her voice to the younger version of the main character, while Denski, a 15-year-old actress, stars as the older June for the majority of the film.

“I can’t believe it’s actually happening. It’s like a dream,” Denski told Variety. “It was a very long audition process. I got a callback, then a second callback, and that blew my mind. Then I got the call that I got the role, and I was jumping up and down and screaming. I just came home from school, walked through the door, threw my backpack down and my mom told me the big news.”

“Wonder Park” is the first voice acting role in a feature film for both young actresses. Prior to this, Denski had performed in a Lysol commercial and recorded an audiobook, while Mali has appeared in “American Romance” and several TV shorts.

“I love voiceover, it’s fun to play characters with big personalities,” Mali told Variety. “I love playing a character with a big imagination, I was like that when I was younger.”

Co-star Mila KunisConnie Britton, Constance Zimmer, David Bisbal, Rachel Platten and Colleen Ballinger attended the carpet. Kunis, Jennifer Garner, Matthew Broderick,  Kenan Thompson and John Oliver all voice a range of humans, bears, beavers, porcupines and wild boars in the animated movie. In her first performance on a film soundtrack, Grace VanderWaal, the 15-year-old “America’s Got Talent” winner from 2016, recorded a song called “Hideaway” for the film.

“All of them really excelled. The younger cast did really a fantastic job embodying those characters we were chasing,” writer-producer André Nemec told Variety.

Held at the Regency Village Theater in Westwood, the premiere shut down several blocks to host a carnival featuring games, toys and candy for many of the young attendees and their families. Several cast members and executives walked the carpet with their children. Jeong, who voices a beaver named Cooper, told Variety that his twin daughters enjoyed the film.

“They loved how family-based it was. A lot of the things I don’t think about as an actor — the imagery, the backdrop, the flourishes, things I have nothing to do with — they notice that. Sometimes as a narcissistic actor I only focus on my performance, but when you’re looking at it from an appropriate lens, we’re just palettes of paint on the whole rainbow of colors,” he said.

Like Jeong, Ken Hudson Campbell, who has voice acted in “Gravity Falls,” “Baby Bob” and “Dr. Dolittle 2,” also revealed the arguably equally important lesson he gave to the young cast.

“Usually it was which sandwich to have,” he said, “especially the Italian beef.”