Harry Styles had an epiphany about his music career when Billie Eilish shot to stardom.

The As It Was singer felt like he and his One Direction bandmates were young and exciting stars in their heyday between 2010 and 2016, and by the time Billie became huge in 2019, Harry realised he couldn't be described that way anymore.

Speaking to Apple Music's Zane Lowe, the 28-year-old said he was grateful to the Bad Guy hitmaker for making him grow out of his desire to be a newcomer and simply focus on making good music.

"Being in the band, I'd always felt like we were really young. We were just really young, and it was fun and exciting because we were young," he explained. "And I had a moment seeing (Eilish) do this (skyrocket) at such a young age where I felt like, 'I'm not that young anymore.' And for a while it was, 'How do you play that game of remaining exciting?' And I just had a moment where I felt like... 'You're not always going to be the young thing,' I was like, 'Okay. I would like to really think about who I would like to be as a musician.'"

While Harry has met the 20-year-old a couple of times, he hasn't told her how "incredibly thankful" he is to her for liberating him from the earlier confines of his career.

"She's a lot younger than me and there's no point in me going like, 'Okay, how do I get back in?'" he admitted. "She totally broke the spell for me in a way that I'm very grateful for that," he continued. "It just let me go. This is so unbelievably liberating to go, 'I just want to make good music.' That's it. That's what I want to do. And everything else is what it will be. And that's kind of it."