Reese Witherspoon Reflects on 'Unforgettable' 'Walk the Line' Scene With Joaquin Phoenix

Walk the Line, the 2005 biographical drama starring Reese Witherspoon and Joaquin Phoenix as June Carter and Johnny Cash, was released 15 years ago on Wednesday, and Witherspoon took a moment to share a memory from her time on set with her followers on Instagram. Posting a photo of herself and Phoenix in character, Witherspoon shared that she felt "completely transformed" while filming.

"Wow! Today marks 15 years since the release of #WalktheLine," she began before thanking the movie's costume designer, Arianne Phillips, music producer T. Bone Burnett and director James Mangold. "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."

View this post on Instagram

A post shared by Reese Witherspoon (@reesewitherspoon)

Witherspoon added that she will "never forget" filming the proposal scene when Cash asked Carter to marry him on stage during a show. "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," she wrote. "You could hear a pin drop. Thank you to the entire cast and crew for bringing Johnny & June's love story to life." Phillips commented, "thanks to @reesewitherspoon for your incredible collaboration AND patience with so many fittings + the indelible magic & reverence you brought to that role."

Walk the Line earned $187 million worldwide and netted five Oscar nominations including nods for Witherspoon, Phoenix and Phillips. Witherspoon won the Academy Award for Best Actress, taking home the same honor at the Golden Globes, British Academy Film Awards and Screen Actors Guild Awards.

Speaking to BBC Breakfast, she revealed that singing live was the "most challenging part of the role" for her. "I had to learn to sing: I'd never sung professionally," she recalled, adding that growing up in Nashville made taking on the role of Carter "pretty daunting," as she "grew up knowing the history of June Carter Cash and her family."

The movie's concert scenes were filmed in front of a live audience, and Witherspoon shared that she "had the most terrible stage fright. It started off with about 100 people there, but by the last performance there were two and a half thousand."