The day after Christmas 33-year-old Colin O’Brady of Portland, Ore., finished a bone-chilling, epic journey that previously was deemed impossible.

O'Brady on Wednesday became the first person to traverse Antarctica — alone — without any assistance, trekking across the polar continent in 54 days.

“I don’t know, something overcame me,” O’Brady told the New York Times in a telephone interview after he crossed the finish line. “I just felt locked in for the last 32 hours, like a deep flow state. I didn’t listen to any music — just locked in, like I’m going until I’m done. It was profound, it was beautiful, and it was an amazing way to finish up the project.”

Friends, family and fans had tracked the endurance athlete’s 930-mile journey in real time online.

“I did it!” a tearful O’Brady said on a call to his family gathered in Portland for the holidays, according to his wife, Jenna Besaw.

“It was an emotional call,” she said. “He seemed overwhelmed by love and gratitude, and he really wanted to say ‘Thank you’ to all of us.”

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.

As for what’s next for O’Brady, who also has summited Mount Everest, Besaw said she’s not entirely sure.

“We are just so in the moment celebrating this right now,” she said. “Then we’ll see what’s next on the horizon.”

O’Brady documented his nearly entirely uphill journey — which he called the Impossible First — on his social media.

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 posted.

“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.” — Colin O’Brady, 33, who crossed Antarctica unaided

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 on 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 Nov. 3. He had to haul 375 pounds of gear largely uphill and over sastrugi: wave-like ridges created by wind.

“Not only am I pulling my ... sled all day, but I’m pulling it up and over thousands of these sastrugi speed bumps created by the violent wind,” he wrote in an Instagram post on Nov. 12. “It’s a frustrating process at times, to say the least.”

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.”

On Day 37, or Dec. 9, O’Brady wrote about how much he’s changed, along with 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.”

The Associated Press contributed to this report.