Toby Keith's 'Don't Let the Old Man In' was inspired by Clint Eastwood.

Clint Eastwood

Clint Eastwood

The singer/songwriter revealed he was inspired by a conversation with the 88-year-old actor/director about his latest movie 'The Mule' and his work ethic.

Toby explained he asked Clint how he kept working at his age, explaining: "He said, 'I just get up every morning and go out. And I don't let the old man in'. And I thought, I'm writing that."

Admitted he became obsessed with the song, Toby said: "People were talking to me and they would say, 'Did you hear what I just said?' And I was like, 'No,' because I wasn't listening to any conversations. I was consumed by 'Don't Let the Old Man In.' I worked so hard on it. When I finally sang the line, I thought, it's got to be dark, it's got to be a ballad and it's got to be simple."

Toby was unwell the day he recorded the track but he believes his illness helped to make the song sound even better.

He explained to Billboard: "I was sick as a dog that day. I was coughing and sneezing and thinking, this is terrible. I gave it the best vocal I could that day, and I sent it off. It's a real raspy, sleepy, tired, sick vocal. I said, 'Well now you've got a reference, and I'll go back and put a vocal on it for you.' "

However, Clint loved the song and the recording and immediately asked if he would include it in his movie.

Toby said: "He said, 'I've got a spot in the movie and I'm putting it in there.' And then Warner Bros. called asking did I read the script before I wrote this song because it fits perfectly. He wanted it sick and tired and dark like that."

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