Ben Saunders may have taken an unusual route to become a modern polar explorer and climate investor. But then again, what would be the usual route?

Saunders, 44, grew up in rural England on the border of Somerset and Devon, before eventually moving to London. There, jobs as a personal trainer came alongside a fledgling career: taking months-long trips into the polar regions. He spoke to Fortune shortly after returning from a trip via icebreaker to the Antarctic about the highs and lows of how he turned a passion into an unlikely career—from the very beginning.

Early years

Saunders started his career as the family milk boy, collecting milk from local farms for 50p a week; then moved onto local paper delivery. By his teens, he had had jobs picking fruit on farms and working in a bike store and outdoor outfitters—an early exposure to outdoor gear and a chance for a naturally shy kid to learn how to work with people.

Both jobs represented an early chance to “geek out,” he says. “They were disastrous jobs in some ways because I’m pretty sure my entire paycheck just went back into the till,” as he stocked up on gear.

By the time he left school—with underwhelming results on his exams—he was 18 and looking for a job in Kent, outside London. Despite his clear outdoorsy bent, he applied for a job at a men’s tailoring shop.

“[The owner] almost laughed me out of the door. I went home with my tail between my legs,” Saunders said. But the tailor ended up needing staff, so he got a six month “crash course” in menswear, complete with an “insane” wardrobe featuring a made-to-measure pinstripe suit.

It was a game changer, Saunders said: he saw how people looked at him differently in the right clothes, and it was an early introduction in how to “pass” in an English society obsessed with class.

But the outdoors called, and by 18, the start of his career of adventuring was born: at a retreat on the northwest coast of Scotland run by a “larger than life” character called John Ridgway, who had been one of the first people in the world to row across the Atlantic. The camp was staffed by young adults, who took corporate attendees kayaking and adventuring.

“That was the year where the screw came loose, really, for me, and I thought—this is what I want to do,” he said. “It was one of the most important jobs of my life. And also, one of the worst paid.”

The year in Scotland also led to Sandhurst, the famous U.K. officers’ academy—an illustrious goal for a kid with no family connections or fancy school, Saunders points out. It was a bust: he lasted 11 months.

By the time he was in his early 20s, out of Sandhurst, he was back in the outdoor equipment shop—and felt he’d come full circle.

“That was around the first time I started talking about my first expedition. I was 21 at this stage, and people thought I’d totally lost the plot,” Saunders says.

“The only way out was through”

By 2001, still in his early 20s, Saunders had moved to London, built up his own business as a personal trainer, and briefly gone to work for a company that did team building workshops. Then, he finally got an opportunity to join an expedition which would go from Russia to the North Pole. He fundraised and pitched for time off work to take the trip, but little went according to plan.

“We didn’t get to the North Pole. We got two thirds of the way there,” he said, after spending 59 days on the Arctic Ocean. By age 23, back in London, “a bit shellshocked by this experience of not getting to the North Pole”, he was handed an invoice for more than GBP 34,000 ($46,000) of unexpected expenses for the trip, and fired from his job.

“They fired me after a few weeks, because I was sat there thinking: how I’m going to get out of this mess?” he says. “By that point, I was in so much trouble, the only way out was through.”

But despite that disastrous first expedition, Saunders picked back up where he left, working as a trainer and raising sponsorships and funding to once again go back to the Arctic. In 2003, he reached the North Pole—this time, they flew most of the way there, he qualifies—and in 2004, age 26, he finally went “pro”—heading to the North Pole via Russia, a trip that involved 72 nights and 600 miles of traveling alone.

He would go on to lead a total of 12 major expeditions to the polar regions over two decades, stretching across 4,500 miles in the Arctic, Greenland, and Antarctica, and to hold the record for the longest solo Arctic journey by a Brit.

That first trip, however, was also when he discovered the easiest route to being a professional explorer: he started speaking.

“I certainly didn’t do my first expedition thinking, great, I can get on the speaker’s circuit,” he says. “I didn’t know it existed. And also, back then it would have sounded terrifying to me the idea of flying around talking to huge groups of strangers for an hour, with no notes.”

But an early appearance at a school gave him the thrill of telling people about the Arctic Ocean, and the thrill of knowing something.

The expeditions gained force, and so did the team, which grew steadily. Between 2012 and 2015 was the “peak of insanity”, Saunders says, with 12 people on his team.

“I inadvertently became the CEO of this peculiar business where I was the boss, and I was the product,” he points out.

The final expedition

In 2013-2014, Saunders went on his most challenging expedition. He and the explorer and endurance athlete Tarka L’Herpiniere went to Antarctica to conduct the longest ever polar journey entirely on foot, an expedition that also cost roughly 2 and a half million British pounds ($3.4 million), he says.

To make it happen—and to survive a trip that lasted 16 weeks—Saunders says required “absolute tunnel vision.” But he’s wary of recommending that approach to a career.

“I’m not necessarily advocating that as advice, because it was a deeply unbalanced way to live, for many, many years, and it was to the utter exclusion of a lot of other things in my life,” he says. “My life was all about one thing for 20 years. In many ways it was a selfish pursuit of personal ambitions and achievements. And it was also, I think early on, sort of ego driven.”

At 23, he points out, he had no qualifications, no money, no connections.

“I think at that point, I kind of made the mistaken assumption that, that if I could just achieve the right thing, and do something impressive enough, and enough people said good things about what I’d done, then then I’d sort of feel happier,” he adds. “And of course, that was completely ludicrous thing to assume, but that was that was how it started. That was the motivation.”

Following a final solo trip to the South Pole in 2017, Saunders has scaled back on the record-breaking expeditions. He developed sponsorships and partnerships with Land Rover and Canada Goose, and still regularly speaks about the polar regions. His personal life changed, too. Four years ago, he got married.

Saunders still speaks and has other partnerships, but this year, he started on what he says is his “weirdest” adventure ever—as a partner at Park Vale Capital, working on investments in early-stage companies focused on solutions to climate change.

He had grown wary of polar expeditions claiming to have a purpose in building awareness of climate change, and wanted a chance to make an impact. He also saw a chance to use the “bonkers rolodex” he’s built up over years of fundraising and building teams to go to the Polar Regions, a process not so different, as it turns out, from putting together presentations for investors.

It’s a new path, he says, and he admits he’s once again struggling with the “imposter syndrome” that’s dogged him from the beginning of his career—and often pushed him on. He said he worried people would ask him, “You don’t have any qualifications, do you? And you’ve just been dragging a sled for 20 years?”

But he says most people have felt the move was obvious, that “of course” he would want to devote himself to climate investing, after seeing the polar regions change over so many years. And he’s excited to have to prove himself, once again.

“I’m sort of back at square one,” he says with a grin.