An American explorer just became the first person to cross Antarctica alone and unaided. He finished the 932-mile journey with an ultramarathon.

The Antarctic crossing is not O'Brady first world record. In 2016, he trekked to the top of the highest peaks on all seven continents, including Everest and Antarctica, in just 132 days. That earned him a world record for fastest climb of the seven summits.

On this journey, O'Brady wasn't going for speed.

"When you have a 400-pound sled, there's no running. It's very slow going," he said. He trained for harsh Antarctic conditions in Greenland by doing a 30-day, 400-mile practice run.

Still, there was no way to prepare for the complete solitude he'd endure during his 54 days in Antarctica.

O'Brady moved with impressive speed. His original plan was to finish the journey in January, taking about 70 days for the trek. But he completed it weeks ahead of schedule.

When he began his trek, O'Brady's sled weighed 400 pounds. Of that, 220 pounds were food — enough to last him for more than two months. He also hauled a tent, sleeping bag, cameras, satellite phone, and 30 pounds of fuel for cooking.

With average temperatures in Antarctica dipping below -18 degrees Fahrenheit, water instantly turns to ice. O'Brady showed his followers what that looks like four days in to the trek.

Whiteouts were a frequent bother. O'Brady said being in Antarctica can feel like standing inside a ping pong ball. Sometimes wind and visibility were so bad that O'Brady had to stop hiking and set up camp in the storm.

The food was not O'Brady's favorite part of the mission. He subsisted on a diet of oatmeal, freeze-dried meals, and special 1,250-calorie "Colin Bars" that his sponsor, Standard Process supplements, made for him. They're a blend of coconut oil, nuts, seeds, veggie protein, and cocoa powder. O'Brady downed about four bars per day. "Unfortunately, fresh food is a little bit too heavy," he said.

This journey was the longest the adventurer ever went without human contact. "The longer I’m out here the more clear it becomes. Love is infinite and the key to life is to love as deeply as possible," O'Brady said 31 days into the mission. He drew this heart for his wife, Jenna Besaw, in the snow. She helped him prepare for the journey and was always a phone call away on the trek.

O’Brady revealed some unsavory truths about the journey along the way. For one, he only brought a single pair of underwear along. Using the bathroom was also a strange chore, since Antarctic explorers carry out every single piece of waste they create. That includes what comes out their rear end. “As an environmentalist, I love this ethic,” O’Brady wrote on Instagram. “Practically speaking, it’s a little undignified as it means pooping into a ‘wag bag’ and carrying it with me.”

That means that even as O'Brady's sled emptied of food, his load didn't necessarily get lighter. Fortunately, with average temperatures well below freezing in Antarctica, his feces probably didn't have much of a smell.

O'Brady's pace quickened after he reached the South Pole on December 12. It took him roughly 40 days to reach that point. "Today has quite honestly been one of the best days of my entire life," he said when he reached the marker.

Ten days ago, O’Brady mentioned in an Instagram post that he had “just enough” food to “hopefully” get him to the end. “Every calorie is precious at this point,” he said.

He battled fierce Antarctic storms, but he recently said he'd tapped into a “flow.” Just four days ago, O'Brady posted this selfie and said, "despite the constant 40mph wind gusts and -25 temperature. I tapped into one of the deepest flow states of my life." He had traveled over 33 miles in 13 hours at that point.

O'Brady said his new record would never have been possible without a healthy mind and body. He bulked up with 20 extra pounds of muscle before heading to Antarctica. "Despite feeling exhausted and worn out, I’m grateful for having lived a healthy lifestyle, for without that I’m certain my body would have given up by now," he said.

Eighty miles from the finish, O'Brady embarked on a final ultramarathon to end his record-breaking quest. "I called home and talked to my mom, sister and wife — I promised them I will stop when I need to," he said.

After 54 days of trekking, O'Brady arrived at the Leverett Glacier Wednesday, with 932 miles behind him.

"I am not unique in this ability" O'Brady recently said on Instagram. "We all have reservoirs of untapped potential and our bodies and spirits are capable of so much more than lies on the surface."