Matthew Ahn had a lot riding on a recent summer commute. The 25-year-old lawyer set out to break his own Guinness World Record for the fastest time spent traveling to every single subway stop on 24 train lines in New York City’s sprawling 469-station system throughout five boroughs. In July, he succeeded with a total time of 21 hours, 28 minutes, and 14 seconds—and he recently received official confirmation as the record holder, according to The New York Times.

Armed with a GoPro strapped to his chest, an iPhone, five granola bars for an energy boost, and numerous bottles of water, the aspiring cartographer created a detailed spreadsheet and itinerary of subway timetables and routes (which he’s keeping to himself as a secret) to help him break the record. His journey started at 2:02 a.m. at Far Rockaway-Mott Avenue on the A train and ended more than 21 hours later at Flushing-Main Street on the 7 train, both in Queens.

Ahn tried to adhere to Guinness’s strict rules—which include witness signatures, time-stamped photos, and a detailed log of the opening and closing of each subway door—all while trying to complete the world-breaking journey on one of the hottest days of the summer, with temperatures reaching a scorching 93 degrees. He also had to run a total of eight miles between stations to get the most out of his time, instead of waiting for out-of-the-way transfers.

Ahn was in a race against himself. His previous world record, totaling 21 hours, 49 minutes, and 35 seconds, was nullified when the 34th Street-Hudson Yards subway stop in Manhattan was opened in September 2015. This time he managed to shave 21 minutes and 21 seconds off his previous total time.

“I would like all the food, and then I would like to sleep,” Ahn said as soon as he completed his trip. “That would be great!” Watch Matthew Ahn in action in the video below.

[h/t Travel+Leisure]

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