Jake Gyllenhaal breezes into the room and pulls up a chair. He makes a quip about the wooden furnishings in our surroundings and, as he takes his seat, exudes the air of a man who is very contented with his lot. And why wouldn’t he be? At 29, the Californian has already shown an enduring quality in his work, from his breakout role in Donnie Darko, through big-budget thrillers such as Rendition and smaller, critically acclaimed films such as Jarhead and Brothers.

Then there is Brokeback Mountain, the film which earned him an Oscar nomination for best supporting actor and cemented his reputation of serious credibility. Now he’s become an action hero, playing the lead in Prince of Persia: The Sands of Time, Jerry Bruckheimer‘s adaptation of the bestselling video game.

Gyllenhaal also appears to have resolved something within himself. Often said to be a somewhat reticent interviewee, today he is open and engaging, humorous and genuine. He talks repeatedly in his soft voice about how he no longer takes himself quite so seriously and how he has learned to embrace the various facets of his career and the life he leads around that.

Long touted to become one of the actors of his generation, someone who will remain at the forefront of the industry when all the other fly-by-night teen heartthrobs have added “Don’t you know who I am?” to their most-used phrases, Gyllenhaal has earned widespread praise.

Jim Sheridan, who directed him in Brothers, compares him to Warren Beatty. Ben Kingsley says he is the classic American film actor, while Four Weddings and a Funeral director Mike Newell, who worked with Gyllenhaal on Prince of Persia, believes that the Californian has the versatility to become one of the greats.

“Jake has this wonderful thing where he can appear in any kind of movie,” Newell says. “Now he’s proved that he can be a star in this kind of movie, and we know he can give a smaller more interior performance. He is very multi-faceted and multi-talented.”

Prince of Persia is certainly a new avenue for Gyllenhaal. Once Bruckheimer decided he wanted him as the lead there wasn’t much of a decision to make. “He’s the king of Hollywood and he decided he wanted me to be the Prince of Persia. It was quite flattering.

“The appeal of playing this part for me was feeling that eight-year-old side of myself. I didn’t really get the chance to in Brothers or Jarhead or Brokeback Mountain. I don’t really think they were for eight-year-olds. This was really an opportunity to go to that side of myself which I felt was a little tired of taking myself so seriously.”

He has starred in a big popcorn blockbuster before of course — Roland Emmerich‘s environmental disaster flick The Day After Tomorrow — but never the sort of action hero lead he has seemed to crave for quite some time.

He auditioned for the part of Batman in Christopher Nolan‘s re-imagining of the Caped Crusader but ultimately lost out to Christian Bale. He is also believed to have wanted the Spider-Man role which went to Tobey Maguire.

“Those are obviously high-profile things where I think the casting of the movie, because it’s its own entity, is so interesting to people. I’ve wanted to do a lot of movies that I haven’t done.”

There are downsides, however, to playing the lead role in a movie of this scale. A six-month shoot in the gruelling Moroccan heat took its toll. He was required to beef up his frame with a rigorous training schedule although he insists “it was never hard to get paid to get in shape”.

Then there is the sheer volume of publicity required to ensure that the movie recoups its reported $250m budget, and questions about his personal life are never far away.

The questions generally relate to his relationship with Reese Witherspoon, which ended last year despite, by some accounts, Gyllenhaal’s desire to marry the actress he worked with on Rendition.

“I don’t know if that’s true,” he says when asked if a film like this brings more prying eyes. “There is a bigger crew, a bigger movie, more journalists, more interviews, but answering questions about my personal life is still my choice, no matter how many questions come I still have an opportunity to decide whether I’m going to answer them.”

On the face of it, Gyllenhaal seems a typical Los Angeles movie star. His parents are both in the industry — his father is the Swedish-born director Stephen Gyllenhaal and his mother the screenwriter Naomi Foner, who received an Oscar nomination for the River Phoenix movie Running on Empty.

He and his equally successful older sister, Maggie, have been performing on screen since they were children but, unlike many of his ilk, Gyllenhaal seems to have a social conscience wider than the world of Hollywood. At times he even seems slightly apologetic about his profession. “It is so hard to be an actor,” he jokes at one point, before pleading to “please put irony in that quote” in case anyone takes it at face value.

One aspect of his life that has emerged during the publicity process for this film is that his parents have divorced after 32 years of marriage. “I think it takes a lot of courage for my parents to make the decision that they made,” he told GQ last month. He has also spoken for the first time about the death of his friend and Brokeback Mountain co-star, Heath Ledger (he is godfather to Ledger’s child).

Gyllenhaal’s apparent contentment could be born of many things. He tries to meditate every day and seems to have resolved some of the issues he had surrounding his work. He has also stated that being around Witherspoon’s children helped him mature.

“In my life right now I feel much more open and for the first time I feel like, ‘This is my job.’ It’s what I do and it’s what I love. My job requires certain things of me and there’s no complaining involved. Previously I had ideas of what I thought an actor was supposed to do.

“At a certain point I went, ‘Wait a second, I’m not really listening to myself. I’m doing something that I think people are supposed to do but what do I really enjoy?’ Let me experience it and decide for myself before I start assuming one thing is cool and another thing is not.

“One of the things which got me into this movie was I went, ‘This is really fun.’ The younger version of me would have been, ‘Oh no, I’m only going to do this movie with that person’ or ‘It’s going to be about that and it’s going to be tortured.’ As I get a little older I’m like, ‘You know what? I want to have fun.’ I don’t really take myself as seriously anymore and as I’ve opened myself up to those things I’ve realised this is an amazing job.”

Part of that realisation may come with age. He will be 30 in October and regards that event as a “crossroads”.

“I feel honoured because I think life is precious and the more years you get you actually begin to learn. I feel that at 29 going into 30 I now have perspective behind me and in front of me. Whereas before I could only see in front of me. Now I’m like ‘Oh, wow. Regret!’

“It feels like a big thing. They say in Ouarzazate [one of the Moroccan locations for Prince of Persia] it is the Gate of the Sahara. It feels a little bit like that in my life, like I’m entering a new gate.”

So, as he approaches his fourth decade, does he feel he has achieved the things he thought he would achieve when he was 20? “I didn’t ever think I was going to be 30 when I was 20.”

What about 10 years from now? What are his aims for then? “I’m never going to be 40.”

Prince of Persia: The Sands of Time is released on Friday