"That's all right, they'll go away." She pauses. "You have to be really resilient to get through something like that, and just have to kind of really surrender to it."
Winslet compared notes with former Titanic co-star, DiCaprio. Much was made of his manly endurance for jumping off cliffs, sleeping in animal carcasses, and eating Bison parts for his role in The Revenant, for which he won an Oscar in 2016.
"We texted each other. I would send him photos every week. I'd say, 'This one's for you, honey!' and I'd send a picture of me hanging off the mountain. He'd send lots of cold-looking emojis back.
"We'd swap lots of stories," she smiles. "It's lovely when that happens because we've both had [as she has had with lots of other actor friends] quite extreme circumstances on some of the films that we've done. So you end up ringing around each other and saying, 'Did you do this? How did you manage that?' I felt lucky to be able to pick his brain."
This year marks the 20th anniversary of Titanic, which remains the second highest grossing film of all time (following Avatar). "I turned 21 on that film and we had a party." She shrugs. "I don't remember anything outrageous happening that night, which probably means I had a hangover."
The Mountain Between Us, released later this year, is about two strangers, a surgeon (Idris Elba) and a journalist (Winslet) who live through a plane crash and have to survive in extreme conditions.
When they realise no one is coming to their rescue, they must forge a bond and trek through the snow for hundreds of miles.
The role called for Winslet to leave her vanity at the door.
"Yeah. Some days I would look really truly gross which I think was rather horrifying to [the people at] Fox."
Winslet's heroics are not only contained on the screen. In 2011, while on Sir Richard Branson's island in the Caribbean, she came to the assistance of his then 90-year-old mother, pulling her out of her house when a fire broke out.
"That probably is the biggest crisis that I can compare in any way to the story of this film. It definitely makes a person much more anxious. I'm now definitely paranoid about house fires, which I didn't used to be at all, so I will constantly make sure I've turned off the stove, blown out all the candles, and I'm always unplugging hairdryers and hot tongs obsessively. I'll check them three times to make sure that I really did unplug them," she says emphatically. "Going through a crisis like that does impact on people."
