It's a grey day in London, and several journalists are huddled anxiously around a TV as Donald Trump steps up to deliver his inauguration address.

In the room next door, Matthew McConaughey is sat in an armchair looking tired. He's three days into interviews promoting his new film Gold, and the process is getting old. It always does.

He stands up slowly as I enter, shakes my hand. He's wearing a black shirt and jeans, has a well-groomed beard and long hair. He is – as is usually the way of things – slightly shorter than you expect.

"Hey man. Is our new president talking yet?"

Yes, I tell him. The new president is about to speak.

"Damn. I'd have liked to seen that."

I offer to wait – for a bizarre moment I imagine us sat here watching it together in his suite – but he shakes his head softly.

"It's OK. I imagine he'll be talkin' for a looong time…"

I open our interview with a question about the considerable weight McConaughey put on to play the role of prospector Kenny Wells. It is a mistake. McConaughey's eyes gloss over as he sits upright in his chair and answers a question he has been asked continuously for days now, possibly weeks. Something about enjoying all the beer and hamburgers. Autopilot.

Against the window, rain falls silently. In the other room a cloud is forming over history. And I am sat in a chair, boring Matthew McConaughey.

Following McConaughey's career – from that early, defining role as the cool elder in teen comedy Dazed and Confused, through the beef cake rom-com phase; the subsequent, self-enforced withdrawal from Hollywood and out the other side to 2013's much written about 'McConaissance,' the hot streak that culminated in an Oscar for Dallas Buyer's Club – you develop the idea of the 47-year-old as a wisecracking Southern raconteur, a good time Texan forever tipping his stetson at life. I wonder: where is that guy?

Time is running out. Something of the hopelessness in the other room has followed me in here. I decide to forget all the questions I have prepared about the film and his career. McConaughey has repeatedly praised his wife in recent interviews. So what's the secret to a happy relationship, Matthew?

McConaughey's eyes flicker in my direction. He pauses for a beat, then leans forward.

"Respect and a sense of humour," he says crisply.

"Y'know? Life is vexing enough man, it's nice to have a teammate that's rooting for you. Rooting for you to be more you. And for you to be rooting for them to be more them."

I nod. That sounds nice.

"I know a lot of people in relationships – hell, I've been in them myself – where if you're apart and you're having a good time, or you're pulling something off, the other side is not that happy for you because it was independent of them."

Yes. YES.

"Man, I'm fortunate enough to have a wife that, when I succeed independently of her because I am somewhere else, she is as happy for me in that moment as I am. Which allows me to be that happy for her when she pulls something off herself that don't have to do with me."

OK. What about Fatherhood? How do you get that right? I instinctively apologise for the intensity for the question, but he swipes it away with his hand.

"Nah these are easy. Fun."

He leans back and broadens his shoulders for a second, like a man about to mount a rodeo, then gets started.

"When you first have a kid, everyone gives you books, gives you advice. I personally got tired of getting those books and that advice without asking for it, y'know?"

You know those police interview scenes in True Detective? When Rust Cohle is telling a story, all wide eyes and gesticulating arms? In real life that is what McConaughey is like, minus the haunted cynicism. Perhaps Cohle is who he would have become if life hadn't worked out so well.

We're here for a blip, man. Y'know? A blip.
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Bear Grylls//Digital Spy
McConaughey in April 2016

"What I know about fatherhood is this: if you love 'em, you can't really screw up. You're gonna not do some things right. But if that kid knows they're loved inside the house, they're gonna really soar outside the house. They're gonna fly."

He shows me them flying with his hand.

"Let me say this about masculinity," he says a moment later when I ask a slightly garbled question about it.

"Harking it back to having kids. Do you have any kids?"

I don't. I want to.

"When you have your first kid, if you do, and any men out there" – he nods down at my dictaphone – "When you have your first kid – and it happens with each of 'em – those two or three months when they're first born, man is never more masculine than at that time. And I don't mean 'macho'. I mean when the heart and head are aligned.

"So whatever you've got going on in your career, those few months after you've had your first born – double down on it. Because your instincts are perfectly in line with your mind. Double down."

When Matthew McConaughey talks to you, he really talks to you. Some people have that gift, and sat opposite him I wonder if that might be the most valuable gift of all.

That all sounds like good advice, I tell him. Has he got any other wisdom he cherishes?

"I've been given a lot of good advice, man… but there is one that's been on my mind a lot lately. This wise old man told me" – here he adopts a slow, wise old man voice with complete sincerity – "'Matthew, I've had thousands of crisises [sic] in my life. And most of 'em never happened.'"

The thing about McConaughey, you quickly realise, is that he really understands timing. The pause between those two sentences is precise.

I nod again - I'm nodding a lot here - so the old man is saying: don't worry about things so much?

"Yeah man! He's saying: we create drama. So many times I've been like 'oh my god this is a crisis', but in fact, when you look back you realise: that wasn't a crisis! I almost developed it into one. I almost turned it into one. But it really wasn't.'

Why did that stick with him? Does he find it hard not to worry?

"I'm a thinker. I can get pretty heady, y'know? But I think that's alright. Because I'm just reminding myself I give a damn. I'm not like 'hey, whatever' – no, I've built things in my life. I'm 47 years old, I've got kids and a family and a career. I've got things that it's my responsibility to protect. So I'm not going to be whimsical with those things.

"At the same time, I find myself worrying about things then a month later, or a year later, or ten years later, think: what were you worried about that for? And usually it's when I'm reminded of my own mortality. Because we're here for a blip, man. Y'know? A blip."

McConaughey's assistant does the celebrity assistant motion for 'wrap things up'. My ten minutes is almost over. Remembering suddenly why I am here, I ask him about the film.

In it, Kenny Wells says he is driven by the pursuit of gold, rather than gold itself. McConaughey has called Wells his favourite role he has ever played. Is it because he sees success the same way?

"There's a poem in the film," he reminds me, "from Tennessee Williams: A bird with no feet sleeps on the wind. Gold is the chase. The making the dream come true. Gold is the getting away with it, the pulling it off. The sticking it to the man. The proving them all wrong. If Wells ever got all the money, it would be the proverbial landing. He'd be dead.

"For me? How is that similar? I'm not much for destinations. I'm asked all the time: wasn't winning an Oscar a destination? I'm like: no, it was a pinnacle part of my career so far, but I didn't look at it like: 'aaah, I made it'. I didn't feel that. My favourite thing to do is to be on the approach. The best I can measure my own happiness or satisfaction is to have something to look forward to. And be on the way heading somewhere."

I thank him. We both stand up. He shakes my hand and wishes me good luck on my travels.

You can get back to watching the end of the world now, I tell him, suddenly remembering the gloom on the television next door.

McConaughey flashes me a grin.

"It's not the end of the world. It's just a gear change, man. Just a gear change…"