When Elliott (Maisy Stella) ushers in her 18th birthday with a camping excursion à la psilocybin-laced mushrooms, the last thing she expects is her psyche to conjure up an “old ass” version of herself (at 39 years old), portrayed by Aubrey Plaza. With her last summer in the picturesque lakeside town of Muskoka, Canada, before she heads off to the University of Toronto, Elliott must tread the warnings of her future self, all while rethinking her misconceptions about love, family, and relationships.

For Park, who conceived of the film following her critically acclaimed debut The Fallout — about the intimate relationship that blossoms between two high schoolers (Jenna Ortega and Maddie Ziegler, also in My Old Ass) in the wake of a mass shooting — the aim was to follow in the tradition of the movies she grew up adulating, from the comparable time-warping 13 Going on 30 to the Robin Williams classic Mrs. Doubtfire.

“I was selfishly making a movie that I wanted to watch, that I wanted to make, and I was hopeful that other people would like it too,” Park says. “But at the end of the day, this is just very personal to me, and subjects that I want to explore, and I want to make a really earnest, feel-good, heartfelt movie that does wear its heart on its sleeve. It’s a North Star for me as a filmmaker now.”

Maisy Stella as Elliott in My Old Ass Photo: MARNI GROSSMAN © AMAZON CONTENT SERVICES LLC

And while the 38-year-old Park — who is perhaps most recognizable as one of the stars of ABC’s late-aughts soapy teen drama The Secret Life of the American Teenager — created My Old Ass for all the various iterations of herself, from her childhood days in Canada to her nostalgia-tinged understanding of new motherhood (she and her husband Tyler Hilton have two children), it’s a film that has resonated across the board.

“I keep joking,” she said, “the amount of old men that love this movie is so surprising, but it’s true! I was at a couple of screenings yesterday, and these very sweet men in their 70s and 80s were coming up to me like, ‘This is my favorite movie I’ve ever seen.’ I’m like, ‘What?’”

Park discusses the inspiration behind the film and being egoless in crafting a narrative that centers young people’s experiences.

You’ve talked before about how making this film is somewhat corrective to the way young people have been portrayed in the past when you were acting. What was that process like for you, approaching the main character and conveying this authenticity that can sometimes be missing?

I was not trying to make a movie about young people, which I think inherently helps. I was trying to tell a human story. I think a lot of people talk down to younger people and don’t give them the credit that they deserve. So I take that very seriously. For many years, when I was acting at that age, I was playing young people, and I was like, “I would never say this, and this does not feel real. I would never wear this. This doesn’t feel authentic in any way to my experience or anyone that I know.” So I try to create, now, an environment, at the very least on set, that’s like, there’s an opportunity for young actors to speak up and say that, and I try to include them in the process.

Can you give me an example from the film?

The Bieber moment (author’s note: the film includes a trip-induced Justin Bieber-inspired montage set to “One Less Lonely Girl”) is a great example. I was talking to Maisy, “What was that moment? What was that concert for you? Who was that artist who really spoke to you?” I think being egoless is the sense where you know what you know but also know what you don’t know and are collaborative and open-minded. I think that’s not only when you create the best art but also when you create the most authentic environment and, hopefully, experience.

How much would you say this film reflects your current self, during the pandemic and in a new era as a mom, and your old self, spending summers in Lake Muskoka?

Definitely, being home in Canada [was part of it.] I didn’t grow up right in Muskoka, but close to there, and I spent my summers there, going to camp there, and [I] went to cottages. And I was like, ‘Gosh, why was I in such a hurry to leave this beautiful place?’ Sometimes, I’m very lucky to have grown up in a place that now I go back to, like, ‘This is so beautiful. I can’t believe I was raised here,’ so there was definitely a part of that for me. It’s not my life story—like, I was not Elliott. I was a very different person at that age. But there’s a part of me in each one of these characters, but I would say, as I was writing, I definitely related more to the “old ass,” older Elliott at this point in my life. But they’re also totally imaginary people. It’s such a weird combination.

Elliott (Maisy Stella) and Kath (Maria Dizzia) in MY OLD ASS Photo: Marni Grossman/Prime Video © AMAZON CONTENT SERVICES LLC

To that end, how did you approach the casting process?

We cast Maisy first. As soon as I saw Maisy, I was like, “Oh, she is Elliott and more.” And so that was a really easy decision, and then it was great because we got to cast every single person in the movie around Maisy, which was so incredible, and she chemistry read with every single character, except for Aubrey, because we knew they were going to have amazing chemistry. It was really important to build it around her, and I think that’s part of why it feels so organic.

What about casting Maddie Ziegler as Ruthie?

Maisy and Maddie Ziegler have been best friends since they were eight years old, and Kerrice [who plays their friend Ro] — they all just kind of fell in love with each other. Having her and Percy [Hynes White] read together was really important as well. Percy was a local Toronto kid, who I didn’t know who he was, and he just sent in a self-tape, and we were all so charmed. Their chemistry was so instantaneous as well. Both Maisy and I adored Aubrey’s work and are huge fans. And then, as soon as I talked to her, I was like, “Oh, she just gets this,” and she is such the tone of the movie, and all the pieces fell together. As soon as they met in person, they hit it off and just really adored each other, which was very sweet to see unfold in real-time. Their humor is very similar, which is awesome.

Kerrice Brooks as Ro, Maisy Stella as Elliott, and Maddie Ziegler as Ruthie in My Old Ass Photo: COURTESY OF AMAZON STUDIOS © AMAZON CONTENT SERVICES LLC

The movie is so tonally wide-ranging. Did adding Maisy’s mushroom trip feel like a critical puzzle piece for you in terms of the believability of this concept?

I wanted it to be a buy-in, but it also had to be a buy-in that felt really grounded and real. So the mushrooms — I don’t know where I thought of it, but I was thinking, if you’re 18, it’s your birthday, it’s your last summer. You’re in Canada, you’re camping with your friends. And [it’s] like, “Yeah.” Once that clicked, it also allowed you to really kind of be like, “Did that happen? Did that not happen?” So the mushrooms [were] a really important thing to get right. We talked about 13 Going on 30 and Mrs. Doubtfire and The Parent Trap — all these movies where the buy-in has to work, and you have to love these characters and these people, and then you don’t really care. You’re just along for the ride. And that was important to get right. The mushrooms just seemed like a perfect fit.

Elliott (Maisy Stella) and Ro (Kerrice Brooks) in MY OLD ASS Photo: Marni Grossman/Prime Video © AMAZON CONTENT SERVICES LLC

The film tackles large, conceptual life concepts, like grief and relationships in a refreshingly earnest way. Is that something you were thinking about as you wrote it?

We wanted to make something earnest. And I think a lot of people don’t think that’s cool?

Yes!

I f—ing love movies like that. Those are the movies that I grew up on. They inspired me so much as an actor, as a human, and as a filmmaker. And I think earnest movies are — yeah, they’re not on trend right now, but I would love them to be, and they’re timeless, hopefully. I want to continue to make really earnest movies, and that was super important to me. as I was writing it, I wanted to tackle those big subject matters but have people hopefully be able to laugh while they’re crying at the same time.

Can you discuss how Amazon MGM and Margot Robbie’s LuckyChap [production company] got involved? I know you have more projects in the pipeline with them.

There’s a reason that they get so much repeat business at LuckyChap with their directors. They’re really, really incredible producers and so, so easy to work with. They have so much trust in their filmmakers, but they’re also really helpful. So it was such a smooth sailing experience that I was like, “Let’s do everything together.” And luckily, they feel the same, which has been really exciting.

Did you pitch them?

They connected after they saw The Fallout and just said, “Do you have any other ideas?” And I just had a very loose logline for this movie, and they said, “We love that. Can we develop it together?” So we put the pitch together and made it with our partners at Indian Paintbrush, and it was such a smooth, incredible process. And then we took it to Sundance [in January] and found our home at Amazon, and it was just such a perfect fit. They really loved the movie. It was so genuine, you could really feel that from them, and they really understood what it was and how to get it to the right audience, and knew how important it was for us to have it out in theaters, and it’s the type of movie that you want to sit in a theater and experience with other people.

With the theater component, there was the Cinespia screening, and there’s such a campfire, cozy, openness, and Gen Z undercurrent to the movie in terms of also dealing with sexuality. Could you speak to any of your favorite moments?

There were so many moments that felt that way. Everyone comes back to me with a different moment that spoke to them in that way, which is really exciting. And it definitely feels like a movie to laugh with a group of people, and to cry with a group of people in a theater setting is really special. What I think is also really cool is it does feel like a movie that you can go see on a date, with your friends, or with your parents.