Gerard Butler thinks it's "best not to" drink or smoke cigarettes.

The 42-year-old Scottish actor has been sober for around 15 years.

Gerard doesn't even think about his former vices in the same light.

"If you drank like I did [in the past] you'd go 'No, probably best not to,' " he told USA Today.

"Once you've been introduced to the art of social drinking you appreciate, 'Well, this is relaxing.' It gets you in the mood. But when you haven't had a drink for a long time, you forget you ever had that. I was [also] a big smoker. I haven't smoked in a long time."

Although Gerard is sober, he still knows how to have a good time.

He doesn't feel like he needs to be intoxicated to enjoy himself.

"Listen, I'm a guy from Scotland," he explained.

"I'm fun-loving, I love people. I love to go out but I love to stay in."

Gerard portrays legendary surfer Frosty Hesson in forthcoming biopic Chasing Mavericks, which will be released in US theatres this weekend.