At 28, Selina Fillinger Is Writing for Both Broadway and TV's The Morning Show : 'It's Been Wild'

Jenny Anderson Selina Fillinger and director Susan Stroman at the Shubert Theatre on Broadway

Playwright Selina Fillinger has had a very busy 2022.

Earlier this year, she was flying back and forth between New York and Los Angeles as she put finishing touches on her first Broadway play, POTUS: Or, Behind Every Great Dumbass Are Seven Women Trying to Keep Him Alive, while contributing to the writers' room for the Apple TV+ series The Morning Show.

"I couldn't even like fully process it until [POTUS] was open and it was happening," Fillinger, 28, tells PEOPLE. "It's extraordinary and so much more than I dreamed would be happening for me at this stage in my career. It's been wild."

The writer, who graduated from Northwestern University in 2016, says that the two major career milestones happened simultaneously. In fact, she admits, "I can't remember which one came first."

Her play POTUS, which was nominated for three Tony Awards at this year's ceremony, was originally in talks to be mounted before the COVID pandemic swept the United States in March 2019. So when the theater industry returned, POTUS announced in March that it would be opening at the Shubert Theatre. Fillinger began at The Morning Show, which stars Reese Witherspoon and Jennifer Aniston, in January.

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Orrin Anderson

"It was like, 'Oh my God, how am I gonna do this?' " Fillinger recalls.

However, she says, "They were two things that I knew were such great opportunities, and I was determined to make it work. I was like, okay, what is youth for if not red eyes, you know?"

Though she says she tries not to "glorify the hustle" — "it's very easy to be like, 'It's exhausting, I haven't eaten' or whatever" — splitting her time between Broadway and Hollywood was "very intense."

Throughout the process, she says, "I became such a better writer because you can't be too precious. You have to churn out stuff quickly, and you have to do it when you're on the plane or running to the next thing."

But if there is one thing that Fillinger has learned, it is to soak in every moment — because you never know what's ahead.

"I tested positive for COVID on our opening night gala [for POTUS]," she says. "And couldn't go to my own opening."

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Paul Kolnik Selina Fillinger and the cast of POTUS, after the play’s first Broadway performance

While she was unable to see her star-studded cast (which includes Lilli Cooper, Lea DeLaria, Rachel Dratch, Julianne Hough, Suzy Nakamura, Julie White and Vanessa Williams under the direction of Tony winner Susan Stroman) take the stage, her parents, her partner and a handful of her friends were in the audience.

"It was such a reminder to take joy in the process and to be present in the process because you don't know if the ending is going to be what you want it to be, or if you're gonna be able to be there," she says, adding: "Truthfully, the process was such a party. And I was so grateful to be working with all these people."

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As for what's next for Fillinger? "One thing about being so young and having this is like, you wanna make sure that you don't peak at 28, right? So I'm really interested in being like, 'Okay, what are the next projects that are gonna cause me to really grow artistically?' And for me, that usually means like, what's a project that scares you because if it scares you, it's gonna mentally sustain you."

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"I think I am increasingly learning how to trust my instincts," she adds. "And I think that's part of growing up."

POTUS: Or, Behind Every Great Dumbass Are Seven Women Trying to Keep Him Alive plays through Aug. 14 at the Shubert Theatre. For more information, visit POTUSBway.com.