A U.S. Navy veteran has smashed two world records after completing one of the most grueling endurance challenges ever attempted — walking lunges across 4.06 miles of Utah’s Bonneville Salt Flats.

Mike McCastle, 38, from Las Vegas, endured nearly 21 hours of nonstop physical punishment to complete the staggering feat, part of his personal “12 Labors Project” — a decade-long mission to perform 12 extreme endurance challenges inspired by the myth of Hercules.

McCastle first broke the record for the most lunges completed in one hour, achieving 3,262 lunges, then shattered the record for the longest distance covered by walking lunges in one hour, reaching 2.22 miles. Not satisfied with two titles, he continued for over 20 hours, ultimately finishing with 4,769 lunges across 4.06 miles — a distance and duration no human has ever achieved in continuous lunges.

Battling exhaustion, searing pain, and even a lightning storm that briefly halted his progress, McCastle took short breaks only to rest, refuel, and recover. His nutrition plan included beef balls, rice, and high-performance gels rich in carbohydrates and protein.

The former air traffic controller and performance coach trained for over three months, dedicating up to 16 hours a day in the gym, preparing his mind and body for what he described as “a mission of willpower, not muscle.”

“This is about showing people that pain and limitation can be overcome with purpose,” McCastle said after completing the challenge. “The hardest battles are always the ones inside your head.”

McCastle’s record-breaking effort marks the ninth labor in his ongoing project, with each challenge designed to test human limits and inspire resilience.