Matthew McConaughey: Big Matt

"I never went in search of fame. It came and bit me in the butt," Matthew McConaughey once said. A law school drop-out, he's had a love-hate relationship with celebrity since he put his legal training to good use, starring as a lawyer in the thriller A Time To Kill 12 years ago.

Admittedly, fame has its benefits – an $8m-per-movie salary, travel, and romantic opportunities with co-stars Penelope Cruz, Ashley Judd and Sandra Bullock. "I guess you could say it [fame] made my life crazy for a couple of years," he sighs, in reference to an incident nine years ago involving nude bongo-playing, after which he was charged with marijuana possession and resisting arrest.

But when McConaughey goes on to complain about a lack of privacy, one wonders whether he protests too much, given his proclivity for on-screen displays of bare-chestedness. Is it a contractual requirement? "Of course not," he replies, impatiently. "If you look at my character, what is it? I'd look pretty funny as a diver with a V-neck sweater on."

Given that his latest role in action comedy Fool's Gold casts him as modern-day treasure hunter, he may have a point. Filming it with Kate Hudson on Australia's Gold Coast certainly provided ample beach time: "That place has a lot of bite to it – in the air, and in the water, and on land. So it was quite the adventure in every respect. It wasn't like you lived up in a hotel, all protected on top of the hill and then came down into the wild – it wasn't like that. We were pretty much at the mercy of Mother Nature, and we had a scare with the irukandji jellyfish, where a couple of people got stung. And we swam with sharks – but they were well fed, which was a good thing for us. Kate had poisonous spiders in her place and I had amethystine pythons in my house, so the whole thing was pretty wild."

McConaughey has always been a nature boy, preferring the outdoors of his native Texas to the classroom. One of three sons born to a schoolteacher mother, his late father had a brief career with pro football team the Green Bay Packers before going into the oil industry. Rejecting a career in the family oil business, McConaughey decided to capitalise on his good looks and charm by becoming an actor.

While at film school in Austin, Texas, a friend cast him in a student project, and this tiny role brought him to Hollywood's attention and a breakout role in Richard Linklater's Dazed and Confused in 1993.

His subsequent career has been hit-and-miss: alongside attention-grabbing roles in Steven Spielberg's Amistad and Robert Zemeckis's Contact, he's played box-office candy in How To Lose a Guy in 10 Days, Sahara and The Wedding Planner.

After A Time To Kill, instead of installing himself in a Beverly Hills mansion, McConaughey backpacked around Peru, and now lives in a trailer. "Once a year, I take a three-week walkabout by myself and don't tell anyone where I am going until I get back. I was a wrestling champion in four villages in Africa during one of my walkabouts. And I love my mobile home. I can feel my independence. It's great having my own four walls instead of staying in hotels all the time. It's not like a five-star hotel, but I like it better," says the actor, who once lived at Hollywood's Chateau Marmont for two years.

McConaughey shrugs off setbacks such as losing out to Leonardo DiCaprio for the lead in Titanic: "At the time, I thought it would suck more than it did. I had a hundred options after A Time To Kill, but then my stock went down. But if I didn't understand that, then I'm in the wrong business. Besides, it made me work harder. I still love Hollywood. It's silly to say it's a world of false and stupid people. Sure, there are swindlers – but you also meet creative and generous people, too. It's a pleasant place to work when you are hip to the game and enjoy it for what it is."

In many ways, acting comes second to McConaughey's pursuit of life itself – surfing, swimming and cycling, launching a range of beachwear, and operating his record label, j k livin – the name based on his personal mantra: "Just keep livin'."

While many actors long to be taken seriously, no one could accuse McConaughey of such lofty ambitions – he makes his debut as a producer later this year with two comedies, Surfer Dude, described as "a wave twisting tale of a soul-searching surfer experiencing an existential crisis", and The Grackle, in which he has cast himself as a bar-room brawler who starts a business settling disputes for people who can't afford a lawyer.

Now, McConaughey is soon to be a father, and the 38-year-old actor wants us to believe he's become responsible. Beneath the public image of a naked, bongo-playing, pot-smoking, heart-breaking beach-bum, he's very different, he pleads: "That's not me. There's a certain amount of structure that I have to have.

"Probably my living in a trailer sounds like I'm just a wanderlust vagabond, but part of it is because I know where my stuff is and how I like it, and there's not enough square footage to have too many places to get lost. So I like to create a world where I'm secure and structured, and do my homework first – just like when I'm preparing for roles; get it all down. I'm a conservative guy in order to live a liberal life.

"My child will spend some nights in the trailer. He's going to have culture and travel, but that's one of the great benefits of my business. Parenthood isn't an exact science. I've got the instincts for it. I'm looking forward to the big baby adventure. Hopefully, I'll make a good daddy. But make no doubt about it: my kid will dance. He will be on the beach and taking wild hikes."

So, we'll still see McConaughey flexing his toned abs on the beach and cycling with his best buddy Lance Armstrong, but he's looking forward to settling down with the 25-year-old mother of his unborn child, the Brazilian model Camila Alves, although not necessarily in the traditional sense. "My parents were divorced twice and married three times to each other," he says. "I believe in the institution [of marriage], but I don't feel you have to marry. A kid just needs a mom and a dad."

Whether parenthood will curb his wild streak remains to be seen. Internet rumours claim that should McConaughey have a boy, he plans to name him Bud after his favourite beer – a tip he picked up from his elder brother, who named his son Miller Lite.

'Fool's Gold' opens on 18 April