Forty-two years ago today (Dec. 21, 1979) was a career-changing day for Willie Nelson: It was on that date that the singer-songwriter made his movie debut in The Electric Horseman, opposite Robert Redford and Jane Fonda.

The Electric Horseman, directed by Sydney Pollack, became one of the highest-grossing films of the year and received a nomination for an Academy Award. In addition to starring in the film, Nelson also contributed several songs, including "My Heroes Have Always Been Cowboys," "Midnight Rider" and "Mammas Don't Let Your Babies Grow Up to Be Cowboys."

Taking his role in The Electric Horseman was the start of an illustrious acting career for Nelson: He's gone on to appear in more than a dozen films, including Red Headed Stranger, Austin Powers: The Spy Who Shagged Me and Blonde Ambition. But in spite of his successes on the big screen, the Texan is humble about his accomplishments.

“I’m the worst actor ever," Nelson insists. "I usually pretty much play myself, whoever I’m supposed to be. And that doesn’t require a lot of acting.”

The soundtrack for The Electric Horseman is available for purchase on Amazon.

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WATCH: Test Your Willie Nelson Knowledge!

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