The actor is known for his roles in films like American Gangster, Body of Lies, and Gladiator, but at 52, he is no longer willing to put himself at risk to shoot his own stunts, because it takes much longer to recover from any injuries.

"I'm an old bloke now, and I used to pride myself on as many 100 per cent shots as I could provide for the director, and I still do, but I have a conversation with the director beforehand, which is like, 'You're dealing with 52-year-old tendons...,'" he explained on U.S. breakfast show Good Morning America.

However, Russell is happy to alter his physique as necessary to suit his movie roles, and that involved piling on 60 pounds (27.2 kilograms) for new buddy comedy The Nice Guys, in which he teamed up with Ryan Gosling and director Shane Black.

"It was just obvious to me that this kind of duo needed something of that traditional, physical difference," he said.

The change of lifestyle actually suited Russell at the time, as he was busy putting the finishing touches to his own movie, 2014 war drama The Water Diviner.

"I didn't do anything special, I just lived the sedentary life," he continued. "Instead of walking, I would take a cab and all that sort of stuff. I was in the middle of post-production of a film that I'd directed, so it was kind of easy for me to have a sedentary lifestyle, just sitting in a room for 18 hours a day, you know?"

Russell goes on to admit the whole process of filming The Nice Guys with Ryan and Shane was a real pleasure: "It was a lot of fun on a daily basis, just getting to enjoy what we were doing," he added.