Having turned 70 last year, Jack Nicholson may well have mortality on his mind already. If not, his latest movie The Bucket List was bound to do the job - it follows two seriously ill men who make a list of things to do before they 'kick the bucket'.

"I think fear of death and fear of the unknown motivates people not to live in the now," says Jack, sunglasses, as usual, fixed in place.

"I always mistrusted someone who said they didn't want to live forever. But I changed my mind when I thought to myself, the real question is not whether you want to live forever, but do you want to live forever at the expense of your children? Because if suddenly people stopped dying, we'd have a real ecological problem on our hands.

"I always thought that was an open and shut question. But, like many of them, I had my mind changed with a little further thought."

These days, Jack doesn't do a lot of movies, averaging about one a year since 2000. Having reached pensionable age with three Oscars to his name, there's not much left for the star to prove, and he knows it. But The Bucket List offered him the chance to work with Morgan Freeman, an actor he has long admired.

"We've known one another a long time," admits Jack. "Morgan and I very much wanted to work together. Sometimes things are great and filming this was one of those times. We both had a lot of awareness of one another. It was a reaffirmation.

"It went pretty quick," he adds. "We worked nice and easy together as we share a lot of the same sensibilities. It makes it easy to move things around when you are comfortable with a person."

The Bucket List also offered Jack the chance to work with director Rob Reiner again, who was at the helm during Jack's legendary performance as Marine Colonel Nathan Jessop in A Few Good Men, alongside Tom Cruise.

"How could I not want to work with Rob?" he asks. "In this case, I was already in before I even read the script, almost. How do you choose what you want to do? It's a different thing as a professional. You only have so many things that are available to you with the time that you have."

After Jack's character, millionaire Edward Cole, meets Morgan's mechanic Carter Chambers in hospital, the pair become unlikely friends and opt to use Edward's cash to make their 'bucket list'.

This sees them jet round the world on an exhaustive trip seeing landmarks like the Egyptian Pyramids and the Great Wall of China, and indulging in skydiving, car racing and getting a tattoo, all with the aid of Jack's long-suffering assistant Thomas (Sean Hayes). "The film has a lot of things in it that people think about that aren't articulated. I thought it was very adventurous and I like to be adventurous," says Jack, although the film's producers have admitted that most of the characters' 'adventures' were filmed in Los Angeles and then completed using a touch of post-production computer wizardry.

But of course the trip isn't just about two men having the time of their lives. They also have to deal with long-forgotten personal issues.

Carter has to deal with his wife Virginia, upset at being left alone at home, and Edward is busy avoiding the prospect of reuniting with his estranged daughter before he dies.

"He's isolated," says Jack. "He says it himself. He knows everybody hates him, or assumes they do. He's had several marriages, which he comments on. It's like anything if you are in that position and of that commitment, as this character is, you really have to make time for something else.

"There was a line I wrote that was cut out of the movie, which was, 'He always understood how people could make money, but he never really knew how to make time.' "What I like about the tone of this movie, and my character, is it's not sentimental, but it has sentiment."

Mention Jack's own personal bucket list, and his thoughts turn to actors he'd like to work with.

"We've all got a bucket list," he admits. "I can't work with Marilyn Monroe, so she's off the list. But there are a lot of people. I was thinking about it last night because people are always asking me which young actors I like.

"I'm categorically against making up lists like that because somebody's always annoyed, so I never answer. But I thought, 'No, I'm going to do this different. I'm going to write out a long list of people, be it Nick Cage or Joaquin Phoenix'. It's, incidentally, a pretty long list."

So, after an acting career which has spanned several decades and given him more adulation, awards and acclaim than most actors can only dream of, does Jack have any regrets?

"I think," he says, "that it's always the things you don't do in life that you regret most, not the things you do."