We all have that one teacher or coach who inspired us, today on World Teacher's Day we celebrate the unsung heroes who make global stars possible
"Going for a 10k run for children with cancer," Burk Gravis WhatsApps, our Olympic Channel interview can wait until he gets back.
It's typical of the man who's dedicated a lifetime to inspiring countless kids through sport and setting some big talents on the right track.
They've all either come through Burk's Whizz Kidz camps or youth clubs, played for his football, athletics, or other sports teams, trained with him, ran with him, laughed with him, and been inspired by him.
Black kids, white kids, Asian kids, Eastern European kids, kids aiming for the Paralympics, many know Burk simply as 'dad', the dad of Haringey London sports.
"We're involved in 29 sports in the London Youth Games, from archery to weightlifting," Gravis says of Haringey Sports Development, the company which he built from nothing.
"Sport lifts you up, it can make you feel like you're walking on air" - Burk Gravis
Haringey is a North London borough of around 300,000 people, and according to the Council, 65.3% of the population is made up of non-white British Ethnic Groups with at least 190 spoken languages.
Haringey is the world, and the world needs sports. It's key to the community, a place where everybody plays together, and at Burk Gravis' clubs, camps, and competitions, everybody is welcome.
He maps out how kids can go from community club to world conqueror.
"It starts in the schools," says Gravis, "where we get the kids interested in sport and participating, then they can compete for the school or join a club, if we don't have a club in the borough, we build one in the school."
"Then they can compete in the London Youth Games, in other London events, at club level, then go on to compete for the district. And then they can go on to international level."
I say to the kids, no matter what your situation is, always believe in yourself, always believe nothing is impossible and live the dream. - Burk Gravis
"So we're starting from the basics, what we have to do is give the kid the opportunity of achieving at the top level. How are you going to get to the top if you don't have the clubs as a stepping stone?
"How are you going to get to the clubs if you don't have enough coaches, so we run a volunteering program as well."
Without people like Burk Gravis, sport simply wouldn't work. His passion and dedication come from his own love of sport.
"When I did my first marathon in under three and a half hours, I thought I could walk on water, it gives you so much confidence, gives you so much belief in yourself.
"And that's what we want for the kids, to enjoy it. It helps build character, gives confidence and that is the key to everything we do, is to give the youngster the opportunity of getting to wherever they want to get to, because sport, once you start..."
But it isn't just athletes who have been inspired by this legendary coach, top ESPN, World Soccer and The Guardian journalist and Spanish football commentator Sid Lowe also discovered his love for sport with Burk.
"Burk Gravis IS sport in Haringey," says Sid, "what a diamond geezer."
He played football, ran, played tennis, and tried many other sports with Gravis' Haringey clubs.
"Burk was involved in everything, at the London Youth Games he would run teams across every single sport. The extent of it is just mind boggling. I can't even begin to imagine how many kids have played sport because of Burk."
And Gravis' involvement went way beyond just coaching and organisation.
"The enthusiasm, the fact that he did it as well," continues Sid, "this wasn't just a guy sort of standing there saying 'right, run around a bit,' he'd be in there playing with you, he'd be running around with you. He ran. He still does now. Just fantastically energetic, fantastically enthusiastic."
Burk remembers Sid too, "he's everything that sport was about for me, he had heart, he had desire, and most of all he was a really nice lad, that was the key.
"Sid was a very good footballer, a very good runner, but he was too gung-ho, he picked up too many injuries," he laughs.
If you've heard Sid talking about sport on TV or a podcast, that'll make a lot of sense, and as someone who also transmits a lot of positive energy, you can see where he got at least some of the inspiration.
Sid, like many other kids, did work experience with Burk at his office in Northumberland Park, directly across the road from Tottenham Hotspur's old football ground White Hart Lane.
"Basically working in his office with him for a week and that involved things like sending out leaflets about sports camps, contacting people, promoting sporting events, stuffing envelopes with leaflets.
"And what I really remember is Burk going round and round around singing [Sid sings] 'the best part of breaking up ooh is the making up' and every morning you go in there and he's so full of life!"
It's common for Burk to be stopped in the streets by grown-ups who got into sport or were inspired by Burk.
"One lady said to me, oh, I did a 10,000 word dissertation and you helped me," Burk tells the story, "I said, I don't know ten thousand words. How could I?"
"She said, no, it was the experience you gave me."
It wasn't easy for Burk, who was born in Germany, to build what he has.
"I guess I was a refugee," he says, arriving in post-war England in the fifties with his parents. "Germany was kaput."
Every day at school they called the 'alien' register, he was the only one in the building to put up his hand. But he learned English fast and showed everyone that what matters is who you are, and not where you come from.
Burk learned a love for sport early on, and coaching and organising came naturally, "that's the German in me," he jokes, always driven by "the passion in sports itself."
And while he's now a British citizen and walks, talks, and acts like a proud Londoner, he never forgets where he comes from.
Ask Burk what his favourite Olympic moment is and he says "every time Germany win medals! I still very much love my country," before adding that watching Mo Farah, the Brownlee brothers, and Super Saturday were also his highlights of London 2012.
But long before that, while he was coaching kids in 1991 and doing the job he loved, cuts to local funding left him unemployed, and his world fell apart when he lost his father.
"Dad died the 16th of December and I just went out for a seven mile run, cried all the way round and decided, I'm going to do this myself. Dad would wouldn't want me to be like this."
Sid remembers the funeral. "We were 14 or 15 and we all went to the funeral, like genuinely, 15, 20, maybe 30 of us. And maybe I'm a bit more sensitive than kids that age, but I remember thinking that this is kind of quite special that a load of kids who are not Burk's kids... That they go."
"We all came because we care," Sid said to Burk at the time. That mutual respect was proof that the kids Burk Gravis coached became much more than sportsmen and women, they became family.
Picking himself up after losing his dad and his job in the same year, Gravis decided to go it alone and created Haringey Sports Management.
"I was determined to get up and running. I ran a marathon for dad in April and then worked every hour under the sun from my living room with a tiny budget. Working from home is not easy, I've got cats that roam all over the place."
Bit by bit the work grew, the grants came and the support built up, volunteers were mobilised and more and more kids got into sport.
"We rebuilt Haringey from the early 90s where we found it in the gutter to where it is now. We were 31st in the (London) Youth Games back in 1995. We came second last year with the highest points we'd ever achieved."
"At the London 2012, we had three women and two blokes from Haringey playing at the Olympics."
Local sport was boosted by the legacy of the London Games says Burk, "the atmosphere was just incredible. And like the World Cup in 66, it lifted the nation. There was a huge uptake in sports afterwards."
But what about his own legacy? "I've always said I'll never retire, even now, at the age of 71, I still go out running 10k's and 5k's. There was a guy shouted out to me the other day, how'd you do it mate?
"I said, easy, one foot in front of the other."
"My motto always is, working with young people, I treat them how I would treat my son and daughter. And that is with the greatest respect, and make sure they get the best experience.
"Now, youngsters of parents that I used to coach when they were kids are getting their kids into sport. So my legacy has been that I got them into sport. That's what it is for me."
Sid Lowe knows what he means.
"At the time, maybe you're not fully aware of how much he gave to it, but he gave everything and continues to give everything.
"You know, you look back and you think, this was my my life that he helped build. I look at this now, for example, my son, and I think one of the reasons I want him to play football, not because I want him to be the next great player, but because I look back and I think without football, so much of what was my life wouldn't be there.
"So without football and without running, these groups of friends, these experiences, the travelling and all of those kind of things that go together and it's actually as much about socialisation as it is about sports.
"It's a bit of a cliche to talk about values and stuff, but that's really what it is. I think Burk expresses that just better than anyone and the impact he's had on on my life and on the life of so many people is absolutely gigantic.
"And he's a completely brilliant bloke."