James Franco was "incapable of settling down" because he was "so self consumed".

The 39-year-old actor has admitted he struggled to settle down with a partner because he was absorbed in his own world and was "scared" of being "vulnerable", which led him to stay busy to distract his mind.

Speaking to GQ Australia, the dark-haired hunk said: "I was incapable of settling down with anyone because I was so self-consumed before.

"I was incapable of sharing my heart. I was so scared to be vulnerable that I made myself busy every minute of the day, so I had an excuse, But I didn't realise until it started to hurt enough."

And the 'Why Him?' star took on "five billion projects" at the same time to stay preoccupied.

He said: "[I had] five billion projects at once, I was everywhere but present."

But James has revealed his hectic work schedule meant he failed to "enjoy" his successful career.

Speaking about the negative impact of his work life, he explained: "The curse of that is that I actually couldn't enjoy my success ... it was never going to be enough.

"I feel like it's not a total coincidence that I hit my own personal wall at the time that I did -- last November. I think a lot of people have been questioning their lives lately in the States and what they're doing, how they're living."