Liam Payne has told of his struggle to find anything to write about when he embarked on his solo career, because he was feeling "so content" in his personal life.
The One Direction star has been in a relationship with singer Cheryl for nearly two years, but the positive side of his life with her left him unable to channel any strong emotions into his work.
He also described himself as "X Factor's biggest winner" because of their romance.
Payne, 24, told The Telegraph Magazine: "I had a bit of a problem formulating what was going on in my brain into the music at first, because I was so content with everything in my personal life.
"It's easy to spill your guts out on a ballad. But I was thinking, 'Oh God, I'm really happy - what am I going to write about?!'"
He said, of his relationship with 34-year-old Cheryl, with whom he welcomed son Bear in March this year: "It's a ridiculous place to be in.
"She's even more amazing than I thought. I was watching her do Fight For This Love when I was a kid, and now we're together with a kid.
"I feel like I'm X Factor's biggest winner."
Payne and Cheryl first met on The X Factor in 2008, when he was a contestant aged 14, and she was on the judging panel.
He and his One Direction co-stars Harry Styles, Louis Tomlinson and Niall Horan went on a hiatus from the band in early 2016 after five years of success all over the world.
The boy band, which originally included Zayn Malik, was formed on The X Factor in 2010, after Payne returned to audition for a second time.
Payne said of the challenge of embarking on his solo career after One Direction: "When I left the band, I felt a bit stranded.
"It took time, but I know as an artist I am starting fresh now. This is Moment One. It's the start line."
Payne has released two solo singles so far, and is set to release his debut solo album next year.