For Muhammad Ali, it was the day someone stole his bike. For Sebastian Coe, it was watching the 1968 Olympics on television at school. Triggers and turning points are prominent in the story of every champion. And Mo Farah has had more than most.

At 29, Farah carried the hopes of a nation around the 25 lung-bursting laps of the track in the 10,000m final as he raced to gold. Ahead of him stands the chance to make history by doing it again in the 5,000m. Behind him, a journey studded with sacrifice, adversity and despair. Farah’s route to the Games has taken him around the globe and across a planet of emotion.

His Olympic year began in Kenya, in a training camp in the highlands of the Great Rift Valley province. The base was in Iten, a small town 150 miles north-west of Nairobi, where life is spartan and distractions are few. An arch spanning the only tarmac road running through the town says, “Welcome to Iten, Home of Champions”.

The culture and traditions of Iten are best represented by St Patrick’s High School, where the athletics programme has been run for 36 years by the Irish missionary and retired geography teacher Brother Colm O'Connell. He has nurtured four Olympic gold medallists and 25 world champions.

At any time on any day, there will be world-class talent pounding the dusty trails and paths at high altitude, hoping to add their names to the illustrious list that includes David Rudisha, who won Olympic gold over 800m on Thursday night in a new world record time.

When I met him there, Farah was deep in training. “My room is basic: a bed, no TV. I wake up, run, have breakfast, sleep, gym in the afternoon, another run in the evening. That’s it, nothing else. No going to the café, no going for coffee. I just eat, sleep and train.” His exertions began at 7am each day. “When you get out on the roads and trails, there are big groups of locals running everywhere. They all run with great hunger. They know if they don’t, their families don’t eat.”

The main meal each day was ugali, a porridge-like dish made largely of maize. At other times, there were portions of chicken, spinach and rice. Luxuries, like his family, became strangers.

His daughter, Rhianna, cried as he packed his bags to leave for Africa. Six-year-olds are not easily convinced about the need for Daddy to be away from home for so long, whatever the ultimate goal. His wife, Tania, a west-London girl whom he met at school, has described herself as an athletics widow. At such times, Farah has to grow skin as tough as the rhino grazing at the lakeside down the valley. “It’s not easy leaving the family behind. But it’s what you have to do.”

Upheaval has become commonplace. Having failed to reach the Olympic final in the 5,000m in Beijing four years ago, a setback he recalls as the biggest disappointment of his career, Farah took stock. To change his career, he would have to change his life.

He has been to Kenya every year since, but those are short stints. Early last year, he moved with the family from London to Oregon on the US west coast, to a place called Eugene that’s been dubbed Track Town. The main reason was to link up with Cuban-born coach Alberto Salazar, three times a winner of the New York marathon and revered as a guru of running.

At the time, Farah was a double European champion, but London 2012 presented an opportunity like no other. “I could easily have stayed in the UK with my family in a nice house,” says Farah, “but I was willing to take a risk.” Friends – and regular football on TV – would have to be left behind.

Over the past decade and more, Salazar has lifted the standards of distance running in the USA and helped to restore a belief that the East Africans are not invincible. Farah approached him after winning his European 5,000m and 10,000m double in Barcelona in July 2010 and the pair linked up in Oregon seven months later.

In previous world championships, Farah had twice finished within a second-and-a-half of winning a medal. Salazar’s brief was to bridge the gap between near miss and glory. He dissected Farah’s running style and broke it down like an engineer tinkering with a highly prized sports car. An important component of Salazar’s doctrine is running on an underwater treadmill in a tub akin to a jacuzzi. It is designed to reduce the risk of injury and to help Farah’s legs survive a programme of 125 miles a week.

Salazar’s vow that his athlete would improve was no hollow boast. At last year’s world championships in Daegu, South Korea, Farah won gold in the 5,000m and silver in the 10,000m. He had stamped himself as one of the best distance runners in the world, able to take on the Kenyans and Ethiopians, and win.

Back home in the UK, no one’s smile was wider and prouder than Alan Watkinson’s. A PE teacher at Feltham Community College, the school Farah attended in west London, Watkinson introduced him to athletics and became a huge influence. How the two met is an epic story in itself.

Farah’s father, Muktar, had moved the family from Somalia: first to neighbouring Djibouti and then – when Farah was eight – to London. Muktar was a businessman based in London and had met Farah’s mother on a holiday to Somalia. Life was relatively comfortable for the family in Somalia but, as violent kidnappings became more commonplace as part of the civil strife in Mogadishu, he decided the family should leave.

Farah arrived in London knowing only three phrases in English: “Excuse me”, “Where’s the toilet?” and “Come on then”. The last of them secured him a black eye when he challenged the playground bully shortly after he arrived at his Hounslow school. The language barrier also cost Farah success in school cross-country races as, not understanding the signs, he would follow the wrong directions.

Over the years, Watkinson had to cajole Farah – a fervent Arsenal supporter – to focus on athletics. As a compromise, the young Gooner was allowed to play football only if he promised to fulfil his running commitments later. Pupil and teacher remained close long after Farah left school. Watkinson was even best man at Mo and Tania’s wedding two years ago.

Support has also come from Paula Radcliffe, Britain’s marathon world record holder, who was so impressed by Farah’s commitment when they met at national team training camps that she paid for driving lessons to make it easier for him to get to sessions at his local track in Teddington, south-west London.

And just as others have helped him, so he wants to lend a hand, too. Farah returned to Somalia late last year. For Tania and Rhianna, it was a first visit – making a lasting impression. “There were parents cradling starving children,” says Farah. “Mothers were forced to choose which children to save and which to leave at the side of the road.”

Using his new status as a world champion, he was moved to set up the Mo Farah Foundation, with the aim of providing short-term relief while seeking sustainable solutions.

His faith is part of what shapes Farah the man and the athlete. As a committed Muslim, he observes Ramadan, but he has had to make adjustments to suit his ambitions. He will delay fasting, as he did for the world championships at around the same time last year, “making up the days”, as he puts it, after the Olympics have finished.

Victories at London 2012 would deepen the impact Farah can make off the track. No British athlete has ever won the Olympic title over 5,000m or 10,000m, let alone both, with Mike McLeod’s silver over 10,000 in 1984 the best finish. The statistic is a measure of the challenge facing Farah.

After last Saturday's victory, “Mo fever” has taken hold and Farah has a chance to join Usain Bolt as one of the poster boys of the Games. Both men are managed by Irish race agent Ricky Simms, who says Farah has the potential to be Britain’s Bolt.

Farah’s sporting hero Muhammad Ali once said: “The fight is won or lost far away from witnesses – behind the lines, in the gym and out there on the road, long before I dance under those lights.”

Mo Farah has done it in the gym and out there on the road. Now it’s time to dance once more. 

Mike Costello is 5 Live Athletics correspondent

Mo Farah runs in the Men's 5,000m Final at 7:30pm, BBC1, BBC Olympics 1