DWAYNE 'THE ROCK' JOHNSON has admitted quitting wrestling was the ''biggest risk'' of his life.

The 'Moana' star walked away from the WWE in 2004 to embark on an acting career and he was aware at the time the chances of him succeeding were slim.

He admitted on Instagram: ''Retiring from the @wwe when I was 32yrs old was the biggest risk of my life.''

An in an accompanying video, he acknowledged: ''In all likelihood I was going to fail because the odds are always against somebody when you go to Hollywood, especially under those circumstances.''

A decade after quitting the sport, the 48-year-old star returned to the WWE and he admitted it had always been his long-term plan to do so even before his original retirement as he wanted to boost his profile as high as possible, before making a comeback to ''give back'' to the sport.

He explained: ''I felt like, at 32, my Hollywood career was just getting started. If I can leave and quietly retire - it was a hard thing for people to swallow - if I could leave and become successful outside of WWE. I meant I wanted global success, global influence in a very real and powerful way, that was my goal.

''If I was able to then go back to the WWE, but this time as a global entity, I could help bring a greater value to the company of the WWE and bring a greater value to the locker room, the men and women who sacrifice and commit so much to this business.

''I thought if I could come back as a greater asset, it would pay off in so many ways across the board - that was a long term goal I had.

''I called Vince Mcmahon in 2011 and we mapped out a plan to come back for a series of matches.

''I was so excited, this was my opportunity to give back to something that was so good to me.''

The 'Jumanji' actor recalled getting a call from WWE boss Vince McMahon the day after his flagship 2013 'Wrestlemania' bout against John Cena and realising he had achieved his ambition.

He said: ''[Vince said] 'Congratulations, you have just set an all time record in the history of professional wrestling, you shattered box office records, attendance records, congratulations.'

''We hung up and I had a moment, it was so gratifying for me.

''I knew this was the way I could give back to this business and I also knew the effect of that how it brings value to the company, changes the perception of the WWE, then also it increases the pay cheques of everybody in the locker room and that's the bottom line. It meant so much to me that I could add to their bank accounts.''

Dwayne retired from wrestling for good the following year after being defeated by John at 'Wrestlemania' and was delighted to bow out of the sport in the way that he did.

He said: ''We had a match one year later, I went in as WWE champion facing John Cena and I knew it was going to be my very last match in the WWE, but I knew I was going to close out my career in the right way, the respectful way.

''Which was I'm laying on my back, I get beat, 1,2,3, I'm looking up at the stars and I'm counting my blessings.''