The 26-year-old singer thinks he was too "serious" when the group were put together in 2020, which earned him the nickname 'Daddy Directioner,' and he felt he was given a "different job" to his bandmates because it was felt he could handle the responsibility.
Asked what he'd advise his pre-fame self, he said, "I think just have more fun and relax a little bit. I think I was a very serious child, one of those man-childs, I was a man in a child's body pretty early on."
"And I think I would have avoided that stage, to be honest with you. To enter One Direction as that (was) difficult, because it just meant that I got completely a different job to everybody else."
Asked if he felt he was the "grown-up one," he added during his interview with Britain's Glamour online, "That was it. And it was boring. I should have just larked around and thrown plates out the window and stuff! Well, I mean at the start, and then later on a bit less rock and roll."
The "Strip That Down" hitmaker admitted it's been hard to follow the success of the band as a solo artist because they "skyrocketed" but he's grown to realise he doesn't have to meet the same benchmarks now as he did back then.
"It's taught me I think that perseverance will always prevail in that sense. Because it doesn't always go exactly to plan," he admitted. "We were really lucky when we came up, we absolutely skyrocketed. And then, it's been hard to follow that ever since."
"But you know, measuring a failure as well. What is a failure? And people will look at this and, for us sometimes getting a 100,000,000 streams isn't quite what we aim for, but it's still 100,000,000 streams... you have to kind of get a hold of yourself."
"Everything is about perspective at the end of the day, isn't it? That was something I struggled with for a long time, because of how well it went (for the band)."