An Oregon man became the first person to traverse Antarctica alone without any assistance Wednesday, trekking across the polar continent in an epic 54-day journey that was previously deemed impossible.

Colin O'Brady, of Portland, finished the bone-chilling, 930-mile journey as friends, family and fans tracked the endurance athlete's progress in real time online.

“A dream this big is certainly outside of the box,” O’Brady told NBC News in a phone interview Thursday. “It's very remote and extreme and challenging.”

For O’Brady, it didn’t just require that he go deep into Antarctica. He says it demanded he go deep inside of himself, too.

"The biggest challenge was the mental challenge of this, without a doubt," said O'Brady, 33. "Not only am I physically alone, but Antarctica is such a blank landscape, there's nothing really to see, it's just a white canvas day after day. So you end up just being alone in your thoughts."

But, he added, “this project was more than just about myself, this is about inspiring other people. We have 30,000 school kids following along to my nonprofit, and hundreds of thousands if not millions following along on social media and online.”

His wife, Jenna Besaw, was gathered with family in Portland for the holidays when the couple spoke after he completed his mission.

"I did it!" a tearful O'Brady said on a call, according to his wife.

In this photo provided by Colin O'Brady, of Portland., Ore., he poses for a photo while traveling across Antarctica on Dec. 26, 2018. Colin O'Brady / AP

O'Brady, who also has climbed Mount Everest, documented his journey — which he called The Impossible First — on his Instagram page. He wrote Wednesday that he covered the last roughly 80 miles in one big, impromptu final push to the finish line that took well over an entire day.

"While the last 32 hours were some of the most challenging hours of my life, they have quite honestly been some of the best moments I have ever experienced," O'Brady wrote on Instagram.

The day before, he posted that he was "in the zone" and thought he could make it to the end in one go.

"I'm listening to my body and taking care of the details to keep myself safe," he wrote. "I called home and talked to my mom, sister and wife — I promised them I will stop when I need to."

Though others have traversed Antarctica, they either had assistance with reinforced supplies or kites that helped propel them forward.

In 2016, British explorer Henry Worsley died attempting an unassisted solo trip across Antarctica, collapsing from exhaustion toward the end of the trek.

Worsley's friend and fellow English adventurer Louis Rudd is currently attempting an unaided solo in Worsley's honor and was competing against O'Brady to be the first to do it.

Besaw said O'Brady plans to stay in Antarctica until Rudd finishes his trek, hopefully in the next few days.

"It's a small club," she joked. "His intention is to wait for Louis and have kind of a celebratory moment with the only other person on the planet to have accomplished this same thing."

O'Brady described in detail the ups and downs along the way since he began the trek on Nov. 3. He had to haul 375 pounds of gear — largely uphill and over sastrugi, wave-like ridges created by wind.

On Nov. 18, he wrote that he awoke to find his sled completely buried from an all-night blasting of wind and snow. That day he battled a 30 mph headwind for eight hours as he trudged along.

"There were several times I considered stopping, putting my tent back up and calling it a day," he wrote. "I wanted so badly to quit today as I was feeling exhausted and alone, but remembering all of the positivity that so many people have been sending, I took a deep breath and focused on maintaining forward progress one step at a time and managed to finish a full day."

In this photo provided by Colin O'Brady, of Portland., Ore., he speaks on a phone in Antarctica on Dec. 26, 2018. Colin O'Brady / AP

On Day 37, or Dec. 9, O'Brady wrote about how much he's changed, and he posted a selfie in which he looks almost in pain, snow gathered around his furry hat.

"I'm no longer the same person I was when I left on the journey, can you see it in my face?" he wrote. "I've suffered, been deathly afraid, cold and alone. I've laughed and danced, cried tears of joy and been awestruck with love and inspiration."

Though O'Brady had initially thought he'd want a cheeseburger at the end of his nearly impossible journey, Besaw said her husband has been fantasizing about fresh fish and salad because he has mostly been eating freeze-dried foods.

And while he does not expect people to follow in his footsteps, O’Brady said he does hope his trek inspires others.

"Whatever people are dreaming of — love, music, art, culture, entrepreneurship, relationship, it doesn't matter,” he told NBC News. "Dare to dream greatly and you can achieve extraordinary things."