In 2013, a man named Andy Davidhazy hiked the 2,663-mile Pacific Crest Trail. At every mile he took a picture of himself, capturing an amazing transformation.
Davidhazy put all of the photos in a time-lapse video, which captures his whole journey from Mexico to Canada in four minutes.
The hike took him about five months and he lost 50 pounds in the process.
Davidhazy, a photographer and designer, wrote that he did the hike for the challenge. "This was the hardest simple thing I could think of," he said.
"Taking a photo of myself every mile wasn't about vanity, but rather a way for me to fully commit to the whole hike," Davidhazy wrote. "If I were to skip ahead, myself and everyone else would know it."
Davidhazy said the experience was transformative. "I never imagined that doing something so seemingly pointless could have such a profound impact on my life," he wrote.
Watch Davidhazy talk more about his journey here.
Stephanie McNeal is a social news editor for BuzzFeed News and is based in New York.