Leonardo DiCaprio's Biggest Movie Insecurity Revealed as He Marks More Than 35 Years in Showbiz

Leonardo DiCaprio may be one of Hollywood's most acclaimed stars, but even after more than 35 years in the industry, OK! can reveal there's one thing he'll never feel ready to do – get behind the camera.

The 51-year-old actor revealed his biggest creative insecurity was directing during a conversation with Martin Scorsese at TIME magazine's A Year in TIME event in New York City.

DiCaprio, who has worked with his idol Scorsese, 83, on some of the most celebrated films of the last two decades – including The Wolf of Wall Street, The Aviator and Killers of the Flower Moon – confessed he has "never" considered stepping behind the camera because he doubts he could ever match the legendary director's brilliance.

"Some people have asked me if I wanted to direct," DiCaprio said. "I'm like, 'I would never want to direct. I could never do anything close to what Martin Scorsese does. Why would I do that?'"

Those close to the actor say his modesty is sincere, pointing to his deep respect for directors he has worked with throughout his career.

"Leo's the first to admit he's a perfectionist," a longtime collaborator said. "He's so focused on the craft of acting that the idea of taking on another creative responsibility genuinely overwhelms him. He idolizes people like Marty and Clint Eastwood, but he doesn't think he's cut from the same cloth when it comes to directing."

Another industry source described DiCaprio's reluctance as part of his humility.

"He's been at the top for decades, but he still questions himself," our Hollywood mole said. "It's not about fear of failure – it's about his respect for what great directors do. He feels there's a purity in mastering one art form, and for him, that's acting."

DiCaprio explained during the TIME discussion that he sometimes regrets not having taken a step back from acting to study the filmmaking process more closely.

"You play these characters, you try to get into the depth of their soul as much as you possibly can," he said. "And I would've loved to be much more of a voyeur … to watch what [Scorsese does] behind the camera. If I look back on anything, I would've loved to have observed that process behind the camera a lot more."

The actor said working with Scorsese for more than 20 years has been one of his greatest privileges. Together, they've spent months of pre-production time debating ideas and creative directions before cameras even start rolling.

"That's been our process a lot, I think, working together… the ability to almost have a debate for months before and lots of questions, and lots of playing devil's advocate about a way to approach things that may not be the most obvious direction," DiCaprio said. "We're doing that on the new film that we're doing now, but it's been absolutely one of the most profound learning experiences."

Those close to DiCaprio say his insecurity about directing contrasts with his confidence as a performer.

"It's ironic," a friend said. "He can lead a cast with total conviction, but when it comes to directing, he freezes up at the thought. He holds himself to impossible standards – especially when Scorsese's the benchmark he's comparing himself to."

Still, DiCaprio calls working with Scorsese "one of the proudest moments" of his life.

"I grew up watching movies very young – wanting to be an actor," he said. "My father brought me to see Marty's work, along with Mr. [Robert] De Niro's, and said, 'If there's anyone you want to strive to work with in your career, now that you have the capability of doing movies, it's with [Scorsese.]' So I got to see Marty's work very, very early on."