Lien Choong Luen has climbed the world's two highest mountains. But ironically, he finds running an 800m race a potentially tougher challenge.
The 38-year-old Singaporean, who anchored Singapore to a silver medal in the men's 4x400m relay at the Asia Masters Athletics Championships yesterday, said: "I spent the most time training for this (running).
"This is not about completing, it's about competing and the fractional difference between gold and silver. And the element of competing - man versus man - is a different dynamic from man versus nature.
"When I was doing Everest, I spent about one or two months of hard training to be ready.
"But for this, it takes one month of training to see every one second of improvement."
Lien, who topped a field of six to win the men's 800m (35 to 39 years old) on Wednesday, returned to competitive running last October.
Only this time, he wanted to go even faster than his younger days. He had represented Raffles Junior College (1994-1995) in sprinting after first taking up the sport in Secondary 4 at Raffles Institution.
He said: "The goal in coming back is to wind the clock back and beat my 18-year-old self."
So 20 years after his last race in 1995, the target was to better his then-personal best of 2min 6sec in the 800m.
At the Singapore Athletics (SA) inter-club championships in October, the first event on his return, he finished in 2min 12.19sec and his body took three weeks to recover from that effort.
But it did not take long for him to outrun his younger self. At the SA Series 3 in March, he clocked 2:05.10.
Now a management consultant, he had to fit running around his work schedule, which can take up to 16 hours a day. In fact, he even brought his laptop to the National Stadium yesterday.
He said: "For this, I had to train before work at 6am, after work at 1am, and I was even doing it in the haze with a face mask on."
His 800m victory in 2:06.99 was no mean feat.
Just 48 hours earlier, on Monday, he had suffered a slipped disc, which left him bedridden. Up to yesterday, he still could not bend to tie his shoelaces.
But summoning the grit which took him across the Gobi desert in scorching 50 deg C heat (in 2005) and the Arctic (2011), Everest (2010) and K2 (2014), he decided to lace up his shoes anyway.
The former commando officer said: "It was an awful scare. I could have easily quit on Monday. But you don't quit before you're forced to quit.
"I wanted to see if I could run the first 50m. And clearly I could run without too much impairment, though I knew it would not be my best timing and off my PB."
Lien scratched the 400m, which was held on Friday, to rest for yesterday's 4x400m, which the quartet finished in 3:43.61.
The final day of the five-day meet also saw Chan Meng Hui, 86, running in the 200m (85 years old and above) race. Though he finished second in 1:05.86, he was greeted with warm applause.
Chan, who has completed 101 marathons, said: "It's more important to cross the finish line. I don't need to know the timing."
India were the biggest winners with 75 golds, 69 silvers and 72 bronzes. Singapore won 14 golds, including two from the men's 4x100m (40 to 44 and 45 to 49 years old) yesterday.
Said former national javelin thrower Poon Pui Fun, 48, who won two golds (javelin and hammer throw): "It's not so much about getting the gold medal, but I enjoy the thrill of the moment when we are competing."