It took Matthew Ahn 21 hours, 28 minutes and 14 seconds to become a king.

The 25-year-old has broken his own Guinness World Record for the fastest trip to every single subway station in the New York City system.

Ahn prepared for the 21-hour journey by packing five granola bars and planning an intricate itinerary that didn’t leave a single transfer to chance. His route, which is being kept a secret, started at 2:02 a.m. at Far Rockaway-Mott Avenue on the A train and ended almost a full day later at the Flushing-Main Street station on the 7 train.

The New York Times followed Ahn on his journey to all 469 stations and at the end declared him the “King of the Subway.”

The King of the Subway spent hours poring over the subway’s timetables, creating spreadsheets to identify the fastest route.

Last year, Ahn won Guinness World Record with a total travel time of 21 hours, 49 minutes and 35 seconds. This year, thanks to his meticulous planning and experience, he was able to shave 21 minutes off of his time. Even more impressive is that Ahn one more station to visit this time. When he won the world record in 2015, the 34th Street-Hudson Yards stop was not yet open.

But it wasn’t an easy feat for Ahn. He was traveling on a brutally hot day, when temperatures reached 93 degrees (and subway stations can be much hotter), and was required to run a total of eight miles in between stations to maximize efficiency.

But on Friday, the arduous 21 hours became worth it. The Guinness World Record team contacted Ahn and told him that it was official: He was the King of the Subway.

“I would like all of the food and I would like to sleep,” Ahn (understandably) said after breaking his own world record.

Cailey Rizzo writes about travel, art and culture and is the founding editor of The Local Dive. You can follow her on Instagram and Twitter at @misscaileyanne.