Goldie Hawn and Kurt Russell don’t know the secret to a lasting romance.

Kurt Russell and Goldie Hawn

Kurt Russell and Goldie Hawn

The couple have been together for 37 years and are often asked for their tips on keeping the romance alive, but they’ve now admitted they have no idea what their secret is, because if they did, they’d “put it in a bottle and sell it”.

In a joint interview with ‘Extra’, Kurt said: "If we knew that, we'd put it in a bottle, sell it and say, 'So long!’ ”

And Goldie added: "I know people always want the answer to that. The answer lies within you … We're alchemists, you have to be alchemists, you have to be able to turn all kinds of metal into gold, and that's what we have to do.

“Sometimes, it takes a little finagling. Sometimes things don't go your way … but the point is you have to go deeper. You've got to find out what's going to get in the way of a love story.

"It's just being conscious, knowing what you want … Friendship is everything, support, friendship, being there for someone, compassion - empathy is huge.”

Their comments come after Goldie, 75, recently said she fell in love with Kurt because he was so "good with kids”.

The ‘Overboard’ star had two children - Kate Hudson, now 41, and Oliver Hudson, now 44 - with her ex-husband Bill Hudson before she began dating Kurt, and loved the way the 69-year-old actor acted around her brood.

She said: "I loved the way he looked at my children. It was really something special and that was … he’s good with kids. And I was like, 'That was amazing.' I did have a boyfriend at the time. That was hard, as I had to call him and tell him we were done and that I had found somebody and that I was so sorry. And I think you had a girl you were seeing too?”

Goldie - who also has son Wyatt, 34, with Kurt - revealed her relationship with the ‘Tombstone’ star is sustained by their ability to "resolve" arguments amicably.

She shared: "You have to learn how to work your way through an argument and be skilful about it and resolve it. Things happen during a marriage or a union, things that are said that shouldn't have been said, or things that are done that shouldn't have been done, or you feel neglected. If two people really want to be together there's something to cherish, so you keep it fresh by surprising each other. Go to a hotel room, go take a hike. Make something happen that's unusual."