As a boy growing up in rural Kenya, Eliud Kipchoge would run two miles to his school every morning, while his classmates walked.
Living in a mountain village close to the equator, the young man thought little of this high-intensity altitude running.
But the farmer’s lad was taking the first steps on the road to sporting immortality.
Three decades years later, Kipchoge entered the history books with a feat of endurance few thought possible.
In becoming the first person to run a sub two-hour marathon, he had smashed a seemingly unbreakable barrier.
The four-time Olympic champion ran at a remarkably steady pace of around 13.6mph during Saturday’s 26.2 mile run.
That is the equivalent to running 100metres in 17.2 seconds, 422 times.
And he did it all sporting a beaming smile, which he forces himself to do as it encourages the brain to release pain-relieving hormones.
Millions around the world watched in amazement as he sprinted – yes, sprinted – over the finishing line in one hour, 59 minutes and 40 seconds.
Kipchoge, 34, who seemed to have barely broken sweat afterwards, declared: “Today we went to the moon and came back to earth.” Just like the moon landings, this was one small step for one man and one giant leap for mankind.
It was probably the biggest achievement in athletics since Briton Roger Bannister broke the four-minute mile in Oxford in 1954.
But the 5ft 6in tall athlete looked as if he had completed a quiet morning run as he reflected on his achievement.
With his feet shod in controversial Nike ZoomX Vaporfly Next% trainers, which contain a carbon-fibre plate that helps propel him forward, Kipchoge looked as if he could do it all again.
His 140-mile-a-week high-altitude training regime and daily intake of a Kenyan cornmeal porridge called ugali, had clearly paid off.
“I have been training for this for four-and-a-half months,” Kipchoge said.
“I have been putting my heart and mind to run under two hours and make history. I am feeling good.
“After Roger Bannister it took another 65 years to make history,” he added.
“Now I’ve gone under two hours to inspire other people and show the world nobody is limited.”
Back in Kenya thousands poured on to the streets of the capital Nairobi as Kipchoge made history.
On streets usually clogged with traffic, cars stopped so drivers could watch the run on big screens.
Kipchoge’s time was not recognised as a world record because the event was not classed as an official race.
But many now believe he could one day get under two hours in a race that qualifies for world record status.
And Kipchoge reckons others will undoubtedly crack the time now that he is shown it can be done.
Although running is a solo pursuit, this was much a team effort with British influence to the fore.
It was organised and funded by British chemical company Ineos, run by Jim Ratcliffe, and dubbed the Ineos 1.59 challenge.
A group of 41 world-class athletes were choreographed into rotating teams of seven pacemakers to ensure Kipchoge kept the right speed.
They included American Olympic 1500metre champion Matthew Centrowitz, and Paul Chelimo, who took silver in the 5000m at the Rio Games in 2016.
Guided by green laser beams fired from an electric Audi on to the ground to precisely control their pace, they were divided into teams of seven.
Five runners formed an arrowhead in front of Kipchoge to reduce wind resistance while two ran behind him.
It is a tactic common in cycling and much of the planning was done by Brit Dave Brailsford, who runs the Tour de France winning outfit, Team Ineos.
Each group ran in stints of just under three miles as Kipchoge completed 4.4 laps of the 5.97-mile course, in Prater Hauptallee park in the centre of Vienna.
The long straight with loops at the end, has slightly raised banks and was partially resurfaced to help Kipchoge keep pace and avoid injury.
The venue, just 540ft above sea level, and time of year were carefully chosen to offer the best running conditions – cool and still.
To save time, drinks were provided by a bicycle rider with Kipchoge supping a super-rich Swedish energy drink called Maurten, rather than his usual sugary tea.
As the pacemakers peeled away on the final straight, he accelerated, smiling and pointing at the crowd who gave him a rousing reception.
He punched his chest twice and pointed as he crossed the line and ran into the arms of his jubilant wife Grace Sugut, his childhood sweetheart.
But the man nicknamed “the philosopher” by friends because of his love of reading, showed no such emotion during the race.
“I was really calm and trying to go with the pace, not to be crazy or slow,” Kipchoge said.
Asked about the reaction in Kenya, he went on: “Everyone can step out of their door and think positively.”
“We can make this world a beautiful world and a peaceful world.
“My wife and children, I am happy for them to come and witness history.”
It was Kipchoge’s second attempt to break the barrier, having missed out by 26 seconds in Monza, Italy, in 2017.
And he is likely to be handsomely rewarded for cracking it this time.
When he returns to home to the city of Eldoret, in the Rift Valley, Kipchoge may become a Kenyan shilling billionaire – equivalent to £7million.
Bannister, Beamon, Ali... top sport milestones
Eliud Kipchoge’s remarkable time has earned himself a place in the history books alongside the world’s sporting greats.
He is following in the footsteps of the finest ever athletes, including Roger Bannister who, in 1954, ran the first sub-four-minute mile.
In the 1968 Olympics American Bob Beamon leaped over 29ft, a long jump record that stood until for 23 years, until 1991. While Cuban high jumper Javier Sotomayor’s 8ft-plus 1993 world record still stands.
Ten years later Pakistan cricketer Shoaib Akhtar bowled the first 100mph ball, faced by Nick Knight in the 2003 World Cup.
A more sedate but no less impressive achievement came from Tiger Woods in 2001 when he won golf’s grand slam by holding all 4 majors simultaneously.
In F1 Finn Keke Rosberg made history in 1985 by completing a grand prix lap at an average of more than 160mph.
Muhammad Ali began earning his nickname The Greatest at an early age. He was just 22 when he beat Sonny Liston, the youngest boxer to unseat a reigning heavyweight champion.
Romanian Nadia Comaneci was the first gymnast to be awarded a perfect score of 10 at the Olympic Games.
She got six more 10s en route to winning three golds at the Montreal Games in 1976.
Jamaica’s Usain Bolt still holds the 100m world record with a time of 9.58 seconds, set in Berlin in 2009.