He had run for 208 hours 35 minutes, the equivalent of more than eight days. So, when Pan Junfan managed to cross the finish line in Guazhou, Gansu province, on Sept 18, the tears began to flow. Not tears of exhaustion, not tears of frustration, but tears of pride and achievement.

The 513 kilometers he had completed over rugged terrain in northwestern China would challenge the greatest athletes in the world. The challenge was all the greater for Pan, who pulled off the remarkable feat after having part of his right leg amputated following a car accident a few years ago.

During the grueling challenge through the Gobi Desert and the Altun Mountains, the 40-year-old faced temperatures ranging from-20 C at night to 30 C by day, wild animals and even a tornado. About 400 km of the trail is uninhabited.

"I hope that by completing the challenge I can inspire people and tell them that life has limitless possibilities and to not stop trying," Pan says.

Pan called the challenge Chasing the Sun, which indicates that running keeps him from darkness. Under his online username Dujiaopan, he has livestreamed his treks on video-sharing platform Douyin, attracting an audience of over 35 million.

A user named Weixia comments that Pan has completed something impossible for most people and proved that life is too short to hesitate in following one's dreams. Another user comments: "You change my definition about bravery and strength."

Pushing boundaries of extreme endurance, Pan's challenge was originally the Ultra Gobi, which is considered a once-in-a-lifetime experience for many marathon runners. Unfortunately, however, the 400 km, nonstop, self-navigating race was canceled due to the ongoing COVID-19 crisis. After careful consideration and a reconnaissance field trip, Pan contacted the race's organizers and they agreed to reschedule the route and allow him to undertake a solo challenge on Sept 9.

Carrying a backpack containing the bare minimum of equipment he would need, Pan battled sleep deprivation, hypothermia and hallucinations during the journey. He could get supplies－food, prosthesis, spare shoes－at the rest stations, which were staffed with support personnel.

Beginning from the "Mars Camp "in Qinghai province, the ultra extreme course was expanded to more than 500 km over sand dunes, dry valleys, stony plateaus and snowy mountains, finishing in Guazhou. Pan describes the journey as "eyes on heaven, feet in hell".

To deal with the potential dangers, Pan listed 100 risks and solutions before the race. About 24 of them were related to the use of prosthetics, such as possible abrasion and swelling of his limb. During the challenge, he encountered 40 of the risks he listed. He prepared three carbon-fiber prosthetics, one for walking, one for jogging and another for synthetic training.

On the first day, his leg was blistered and its skin was peeling after running for 46 km. The leg was swollen and caused problems with his prosthesis, which he found difficult to get on. In pain, Pan changed it at a rest station.

With just 15 minutes' rest, Pan clocked 26 hours and 3 minutes for his first 102 km, breaking the record set by Spanish amputee athlete, Gorka Zubeldia Letamendia, in last year's Ultra-Trail du Mont-Blanc－a grueling 101 km race that goes from Italy to France.