Rob Lowe "barely" recognises his old self.

Rob Lowe

Rob Lowe

The 56-year-old actor has been sober for over 30 years and he admitted he feels like his days of wild partying took place during "another lifetime" because he's so different now.

Speaking on 'Sunday Sitdown', he quipped: "I was a teen idol, young movie star and an alcoholic [with] a lotta money, and it was a great mix. What could possibly go wrong?"

He then added: "But when I was done, I was done...

“It is legitimately another lifetime. I’ve been sober way longer than half my life.”

The '9-1-1: Lone Star' actor - who has sons Matthew and John with wife Sheryl - thinks fame can have a dark side.

He said: “You either come out on the other side of it way, way, way better or way, way, way worse."

After giving up alcohol at the age of 26, Rob believes the key to staying sober is "you have to want to do it".

Meanwhile, the former 'West Wing' star also repeated his claim Prince Harry has grown a ponytail and joked he wants too land the first pictures of his neighbour's new look.

He said: "I don’t want to stake my long-term credibility as a celebrity stalker.

"However, in the glimpse — and it was a glimpse — through the VIP, sexy, smoke-filled glass of the vehicle, I think the dude was wearing a ponytail.

“Well, here’s what it was. Let’s get specific. Let’s go on a deep dive. The man’s got good hair.

“His brother may be the [future] king of England, but for my money, Harry’s got something better than his brother: hair.

“The British paparazzi are all over this one… There’s gonna be [a] $500,000 bounty on the first photo of Harry with a ponytail, or not… And I’m gonna be the bad guy.”