See Naomi Ackie Become Whitney Houston in I Wanna Dance with Somebody Trailer, First Photos

Naomi Ackie admits she was "very" nervous to play the "incredible, multifaceted" Whitney Houston.

"She's been elevated in my life for so long that it felt like an impossible thing to achieve at times," she tells PEOPLE. "But so many people told me the same thing: If I wasn't scared and nervous, they'd think something was wrong with me. ... The biggest challenge was letting my fear of the magnitude of this task take a back seat. Nothing good comes from sitting in fear for too long."

Ackie, 30, stars as the late singer in the upcoming biopic I Wanna Dance with Somebody. PEOPLE has an exclusive first look and trailer for the film, which hits theaters Dec. 21.

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I Wanna Dance with Somebody is written by Anthony McCarten, the screenwriter behind the 2018 Freddie Mercury biopic Bohemian Rhapsody, and produced by Clive Davis, who is portrayed by Stanley Tucci in the film.

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Ackie says the filmmakers "managed to fit in so many of our favorite songs" from Houston's career into the film, which she says showcases "parts of her life that we know about but through the scope of her own internal world."

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"Fans can expect to see her life like we see are our own. Ups and downs, triumphs and disappointments, all of it mixing together to make up a life," says Ackie.

Director Kasi Lemmons (Harriet) tells PEOPLE it was important for her to capture Houston's "spirit and humanity while celebrating her music and monumental artistry." Lemmons adds that Ackie is "phenomenal" in the role.

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"She completely inhabits the character of Whitney. She put in a year of rigorous preparation so that her transformation onscreen displays effortless virtuosity and is utterly believable," says Lemmons.

"Audiences will get to experience the greatest voice of her generation, singing her most iconic hits, both in the studio and in concert. They'll see how she created that work, to better understand and appreciate her artistic process and singular creative genius. Her fans will love reliving the music while getting an intimate look at the woman behind The Voice. We'll all be reminded how lucky we were to have Whitney with us for the time we did."

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Ackie says she found at least one way to relate to the music legend.

"All Whitney wanted was to sing. I'm convinced that if that was an audience of two or 2 million, she would have felt that connection to her power. It was simple," she says. "I guess, boiled down there was a need to share her gift. I think we have that in common. I just want to act. I want to share that. I worked from that base of commonality."

"Our lives are very different," she adds, "but the drive to share a part of ourselves through different mediums is the same."

I Wanna Dance with Somebody is in theaters Dec. 21.