Playing June Carter Cash was the role of a lifetime for Reese Witherspoon.

On Wednesday, the actress celebrated the 15th anniversary of the release of the Johnny Cash biopic “Walk The Line” with a post on her Instagram account.

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“Wow! Today marks 15 years since the release of #WalktheLine đŸŽ¶,” she wrote in the caption, alongside a photo of herself and Joaquin Phoenix in character together. “Playing the role of June Carter was one of the most rewarding experiences of my lifetime.”

“From the stunning costumes created by @ariannephillips to recording all of those classic country songs with T. Bone Burnett, to the incredible scenes written and directed by James Mangold, I felt completely transformed into an authentic country artist 🌟,” Witherspoon continued.

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“I will never forget the proposal scene… how Joaquin looked with the light beaming behind him asking June to marry him in front of a full audience. You could hear a pin drop,” she added. “Thank you to the entire cast and crew for bringing Johnny & June’s love story to life.”

Witherspoon won the Oscar for Best Actress for her role in the film, which was also nominated for four other awards, including Best Actor, Editing, Sound Mixing and Costume Design.