How do you solve the Peacock problem? It is, it should be said, a pleasant puzzle to wrestle with, but nevertheless it needs a solution. It goes like this. You are an Olympic or Paralympic athlete and this summer you achieved the ultimate, winning gold in a home Games. It is an opportunity given to few, one seized by even fewer. Mission accomplished – so what next? Where on earth do you go now?
It is one by no means unique to Jonnie Peacock – there are plenty of others scratching their heads as winter replaces Britain's golden summer – but we are talking about it, so for the purposes of this discussion it will have his name attached.
"The Olympic depression," says Peacock. "A lot of people get it. You've done what you wanted to do – there is nothing more you can achieve above that. If I go to Rio and get a gold medal it won't be anywhere near as special as a first Games, a home Games. Yes, it would be special, but it's not going to be that special."
It is a refrain familiar to many of those who were embedded in this summer. Jason Kenny, a double gold winner in the velodrome, has admitted struggling to get himself back on to his bike at the age of 24, while Chris Furber, the coach of Britain's Paracyclists, confessed to feeling "empty and directionless". Jessica Ennis called the return to training "horrible".
Peacock does not leave his teens behind until May and the greatest feat he will achieve in his sporting career is behind him. He knows it. On a mild September night, 80,000 people inside the Olympic Stadium chanted his name – something that hadn't happened to Ennis or Mo Farah – before he sprinted to 100m gold in the race of the Games. Such was the cacophony of support that poured from the stands, Peacock had to climb off his blocks to implore them to be quiet so the race could start. That he did so with a large smile spread across his face offers a suggestion as to how he will solve his problem.
Motivation matters in elite sport and finding fuel for the future now occupies the minds of coaches and athletes, especially for a Paralympian who will not perform in front of anything like the London crowd for another four years. One of Peacock's strengths appears to be an ability to live in the moment. He revelled in London. But time to move on – and time is the initial key.
"That's my motivation for the next year or so – running faster," says Peacock, already the world record holder in the T44 class with 10.85sec. "I should have run faster than I did in the Games. I'm still quite new to the sport, we don't know where I am going. I could break at 10.8, maybe hit 10.7 next year and stay there for the rest of my life. But I could run 10.6 then 10.5 the year after that – you never know."
We are sitting in a large room in a Surrey sports club, laid out for a meet-the-athlete session as part of Parafest, an attempt to build on the Games. Peacock has spent an age signing autographs and posing for pictures, smiling and joking throughout for men, women, plenty of children, some disabled, some non-disabled.
"It's cool to see them interested in Paralympic sport," he says. "I never expected this kind of reaction. This is something that really changed my life, when I came to this thing four years ago."
It was at a talent-spotting day at the tiny Mile End Stadium barely a mile from where the Olympic Stadium was being built, that Peacock found himself, and not just as an athlete. It is an experience others are going through as we speak. Earlier, a man in his forties told me how he had never worn shorts before the London Paralympics because he did not like people staring at his prosthetic limb. Today his limb is out and proud.
"That's wicked," says Peacock. "People don't think it's a big deal, but it is. I remember I would never walk around in shorts, people staring. Now people are more proud of who they are. What happened to me, when I came [to Mile End] four years ago and first saw the other amputee guys – cool guys, one was absolutely covered in tattoos and was just standing there wearing shorts with this wicked robot leg standing out – it was the first time I really felt I wasn't different and there were people like me. Regardless of whether I made it to the elite level it did change my life turning up that day. It will be the same for people here."
A record-breaking audience of more than six million watched Peacock's race on Channel 4. It has given his sport an opportunity it has never had – hence Parafest – and it has made Peacock a national figure. "I've seen pictures of kids going to fancy-dress parties with cardboard legs, and another who made a cardboard wheelchair because he wanted to be Dave Weir," he says. "I didn't expect it to be as big as it has been."
So what has it been like? He pauses and shrugs. "Celebrity Juice, going on Alan Carr – these are the things I watch. When they asked me to go on, I was like, 'Why do they want me? I'm not anyone – if I was watching it I wouldn't want to watch me!' It was wicked to see the Paralympics get that. That's a reason why I do it; it's important to recognise the Paralympics and jolt people's memories – remember this."
It is a familiar, and striking, characteristic of many Olympians and Paralympians; how they feel a sense of duty to fly the flag for their sport. They as much as the people who run their sports accept that this is their moment, carpe diem and all that. Yet Peacock is only 19: it must be challenging at times taking an ambassadorial role.
"I know what you mean," he says. "I try and live my life, take each bridge as you come to it. That's what I did last year and that's what I've done this year. Whatever happens, we'll see. But I think it's important for whoever it is to bring recognition to the sport.
"Look at Oscar Pistorius. He was only 18, 19 when he started getting all the attention and he coped brilliantly with it and now he's an ambassador for the whole of Paralympic sport."
On that night – for what Peacock calls the "daddy race", the 100m final – Pistorius was introduced first and received noisy acclaim. Peacock felt the first of three fleeting moments of doubt that evening: did they want him to win more than me? Then he was presented to the crowd and doubt No 1 vanished.
"I was probably the most relaxed I have been because I knew I was prepared. And when the crowd started going crazy it was like, 'Yes, this is mine, this is my track. They want me to win – they don't want Oscar to win.' It was amazing.
"I remember getting to 60m and coming upright and then thinking, 'S**t, I could win this', then seeing the line and thinking, 'Oh God, I could actually win this'. Then at the same time I was thinking, 'Wait, when's Oscar going to come up?'"
That was moment No 2, one that could be counted in a couple of seconds. The third came after he crossed the line. Watch the race back and you see an initial burst of joy, then he slows and stares at the big screen that looms over the finish.
"It was, 'Wait, let's make sure I've actually won before I start celebrating'." He watched the replay. "It felt like a lifetime. I wasn't too sure – maybe someone had slipped up inside me and pipped me at the post. It was about making sure."
The day before we met was his first back in full training since a post-Games ankle operation. He is getting back in business after the post-Games whirl, which included one week of holiday, him and a friend on a road trip around France and Belgium.
"I was living on burgers – burgers and beer, that's all," he says. "It's about enjoying it – that's the most important thing. That's what keeps you in it. If I have a burger once a week and it keeps me in it for 10 more years, then bring it on."
Top five moments of the Paralympics
1 Ellie Simmonds
The 17-year-old was the face of Britain's Paralympic team and she was feeling the pressure. But when it mattered she rose gloriously to the occasion, holding off Victoria Arlen to win the 400m freestyle. The roof nearly came off the Aquatics Centre.
2 Jonnie Peacock
Peacock calls it the "daddy race", the 100m final, and he ruled it. The T43/44 was the best field ever assembled at a Paralympics – Oscar Pistorius finished only fourth – and Peacock produced the performance of his young life to win in 10.90sec.
3 David Weir
Gold No 3 of four – winning the 800m and, like Peacock, leaving a quality field struggling in his wake. His suit was undone as he came off the bend to overtake China's Zhang Lixin and power home. Marcel Hug, the world record holder, could do nothing.
4 Sarah Storey
Gold No 1 of four – it was Britain's first of the Games on day one of the Games. Storey got the home team off to a flying start with an utterly dominant performance in the C5 pursuit, catching her opponent, Poland's Anna Harkowska, before the halfway point of the 3,000m race.
5 Brad Snyder
This is about human achievement as much as sporting achievement. A year to the day after he was blinded by a Taliban bomb, Snyder won freestyle gold. Speaking to him afterwards was to warm to a humble, good man who has rebuilt his life through sport.