When James Stephenson feels himself going too fast as he trains, he turns a dial on his mask and restricts airflow.
It's because he knows he won't be able to breathe all the oxygen he needs when he and his friend Mark Case journey to Mount Everest in April.
The pair, from Mount Gambier in SA's South East, will hike for 14 days from the infamous Lukla airport, travelling through Everest base camp to Kala Patthar where they hope to get a selfie featuring the world's highest mountain.
It's been a trip a decade in the making for the pair, who want to take on the challenge before they get too old.
"Mark's just over 50 and I've just turned 46, so we just want to be able to prove it to ourselves," James says.
"It's great for us getting to the age we are, it just shows that anyone can do it.
"There's no reason why you can't do anything in life.
"Things like this just hopefully push other people around our age who maybe thought about doing it to go out and do it."
Unusual training regime
James and Mark have been friends for a long time and have taken on a lot of different walks, including the Kokoda Track and Tasmania's Overland Track.
Mark regularly takes part in running events up to 25km while James has also taken on the Burma Death Walk, following the route taken by Allied prisoners of war during World War II.
But the training they are taking on for this adventure is very different from what they've done before.
"We knew once we locked it in, we'd have to take that next step," James says.
"So things like ice baths, saunas, hiking, altitude masks and running.
"It's fight or flight when you do things like an ice bath. So it's just that mental strength that you just push yourself to continue to do it."
James says the mask, in particular, inspires some odd looks from locals as he runs around town.
"I heard a lady say to me the other day, 'Is that guy, even though he's on his own, wearing a COVID mask?'," he says.
"It definitely gets people talking when they see me Darth Vadering up around the lakes."
But for Mark, the training will be worth it if it helps them enjoy the trip.
"You don't want to be up there on struggle street. You want to be looking around enjoying things and not puffing and panting like a mangy dog," he says.
Tourists returning
James and Mark will be far from alone, as tourists return to Everest post-COVID.
Australian mountaineer Allan Cohrs runs a tour company taking people on climbing expeditions and treks, including to Everest.
He's summitted Everest, as well as nearby Lhotse and Manaslu — the world's fourth and eighth highest mountains respectively — and is making another expedition to Everest's summit this year.
"Certainly since COVID there's been a rise in the number of people going [to base camp], but it's always been a popular destination because it's achievable for someone without any climbing background," he says.
"You just put a bit of effort in with your training, it's not as big of a financial sacrifice, and it's more attainable for more people.
"It's popular and it's probably gained in popularity, but it's always been a milestone or an objective for a lot of people for many years."
But for Australians looking to journey beyond base camp, Allan says training to prepare for the extremities of Everest can be tough.
"As Australians, we're sort of limited by the ability to get to any significant altitude," he says.
"Our highest mountain is Kosciuszko, which is lower than landing in Lukla.
"To actually train for altitude is not so simple, particularly if you're Australian, so you need to acclimatise slowly when you get to the Himalayas."
Family's concerns
While James and Mark are excited to head to Nepal in April, the plan has been met with apprehension by some loved ones.
"My wife thought she'd be clever and tell [my daughter] how dangerous it is to go to Everest and how many people die a year, and you do literally walk past frozen dead people, especially when you're going further up," James says.
"You know, that's not really nice, hearing it from your nine-year-old daughter, but that didn't stop me.
"But [now] the family and friends are really supportive. They know who Mark and I are.
"We've been the same since we were kids, so everyone who knows us knows that these sorts of things are just part of our life."
Mark says he's excited to share the story once the pair return.
"The plan is to get a photo of us holding a beer, with Mount Everest in the background," he says.
"It's a bit of inspiration for people who want to do it to get out and do it."