Celebrity Celebrity Belief & Identity Celebrity Religion Dennis Quaid on How His Song for 'I Can Only Imagine' Was Inspired By His Rehab Experience The actor's song, "On My Way to Heaven," is featured on the faith-based film's soundtrack By Julie Jordan Julie Jordan Julie Jordan is an Editor at Large for PEOPLE. She has been with the brand for 25 years, writing cover stories and features and managing special issues including the Beautiful Issue and Sexiest Man Alive. People Editorial Guidelines Published on March 28, 2018 04:40PM EDT Actor Dennis Quaid has been writing music since he was 12 years old. His song “On My Way to Heaven” was originally a tribute to his mom, Juanita — but Quaid never finished it. Then the actor signed on to star in the hit faith-based film, I Can Only Imagine, which tells the story behind the MercyMe song of the same title, the bestselling Christian single of all time. “Somehow it all came to me,” Quaid tells PEOPLE of completing the song. “A lot of really good things have transpired that became part of it.” Now his song is featured on the soundtrack of the movie, in which Quaid, 63, plays the abusive father of MercyMe lead singer Bart Millard. The low-budget film has made almost $40 million at the box office and continues to be a sleeper hit. “I’ve never been in a film that’s quite like this before,” Quaid says. “I’m just really grateful and I’m happy for Bart.” Randy Harris Written in the early 90s, “On My Way to Heaven” is also personal for Quaid. “I’d been out of rehab for cocaine for several years so that’s how it came about,” he says. “Anything I write is always about myself or what’s going on in my life or about somebody in my life.” The video for the song was shot at the historic Ryman Theater in Nashville, where Quaid and his band, The Sharks, opened for MercyMe to celebrate the premiere of the film. As a child raised in Houston by his Southern Baptist parents, Quaid fell in love with the music of Elvis Presley, Hank Williams and the Beatles. “I just started writing songs because it seemed natural,” he adds. “That’s how I got through my teenage years.” In 2000, the actor began singing and playing guitar and piano with his band, The Sharks, in between acting gigs. Now almost 18 years later, they continue to perform in venues around the country and hope to release more music this summer with producer T Bone Burnett. “We’re going to be the oldest guys to make it in the music business,” Quaid says, laughing. “I love making movies and I love to act, but playing music is very present. It moves people.” “On My Way to Heaven” “is a song of joy, that’s what it is,” he adds. “It’s just about being grateful.” I Can Only Imagine is currently playing in theaters.