The work of a Formula 1 driver is never done. From the moment the nine-month 2010 season draws to a close with the chequered flag at Yas Marina, the drivers will barely have a moment spare to reflect on the year's 19 races.
Already, their attention will be turned towards next year and a winter cardiovascular training programme aimed at keeping them at fit as possible to handle the surprisingly tough demands of handling a Grand Prix car.
Every driver has a different approach to getting himself in shape and, for Lewis Hamilton, that will predominantly entail running, cycling and hiking near his home in Switzerland.
The mastermind behind the 2008 world champion's fitness regime is Clayton Green, who might sound like an R 'n B singer but is in fact a local lad who grew up around the corner from the state-of-the-art McLaren Technology Centre in Woking, in the English county of Surrey.
Green took on the role of Hamilton's personal trainer only at the start of the year, so this winter will be his first full pre-season training programme session with the McLaren driver and it is a role he is relishing.
"We have a fitness and well-being centre at the MTC and I was managing that and overseeing programmes for the rest of the team," says Green. "But when the opportunity came to travel the world with Lewis Hamilton, it was like a dream."
But just how fit does an F1 driver really have to be? And, driving skills aside, would it be possible to prepare the average man off the street for the rigours of the top tier of motorsport?
"To train someone off the street for F1? That would be a big, big ask," says Green. "The likes of Lewis start driving when they're so young so there's years and years of conditioning there for their backs, necks and shoulders for the unbelievable forces they need to absorb while driving."
Hamilton and teammate Jenson Button are generally regarded as two of the fittest drivers on the grid but how they compare with their rivals in F1 and other sports is, says Green, almost impossible to say.
"Lewis is right up there in terms of his fitness levels but it's always difficult to compare people across sports. But the conditions he faces are pretty extreme. For example, his heart rate is incredibly high in a race - about 85 per cent of the maximum heart rate for the duration of a race, which is similar, say, to a marathon runner."
A tired driver is a driver who can lose control of his vital response times, "So the key is to be cardiovascular fit. What's important is that Lewis has the fitness to be able to make the quick decisions needed throughout a race. If drivers aren't, that can have very serious consequences for them - it can be disastrous, potentially."
This winter, Hamilton will be put through his paces by Green for as much as two training sessions six days a week before the 2011 season opener in Bahrain in March. This is a race in which the driver will lose as much as three kilograms in weight as he sweats in temperatures around the 50-degree mark in the cockpit.
As for how to get the 25-year-old in shape for that kind of ordeal, there are no clear-cut answers.
"It's not like a swimmer that needs to pound lengths and lengths of a pool," says Green. "It's just doing the cardiovascular work that suits the individual and you need to make sure to keep it fresh and fun - it has to be as interesting as possible as there's a lot of it.
"You can do anything from swimming to cross-country skiing. Lewis did some hiking in Courchevel last year and I think the plan is to do some more hiking in Switzerland this winter."
Details are kept deliberately vague. Motorsport is all about finding a crucial edge - whether in the car or the driver - and "I'm not going to give away entirely what we're planning", adds Green.
Nevertheless, it is during the winter that Green can really affect the fortunes of team and driver.
"I'm excited about getting stuck in," he says. "During the season - apart from perhaps the lengthy summer break - I've only been able to get the odd days with Lewis here and there amid racing and his sponsor responsibilities. The winter is when you get a platform to make a real difference."
That said, Green is an ever-present figure beside Hamilton during the course of the season. Usually, whenever the driver is filmed heading to his car for a qualifying session or a race, he tends to be the man at his side; and in the pit lane it is Green who has the responsibility for showing the pit board to Hamilton during the race.
Because of this close working relationship - "it's not quite the case that I see him more than my wife," jokes Green - the two men do have to get on well.
'It's obviously important that you get on with each other and thankfully we do," he says. "But that working relationship has to be there as well. My job is to advise him how best to get fit to drive. I wouldn't tell Lewis how to drive and likewise he lets me tell him what to do, although we can let off steam occasionally."
Such is Hamilton's competitive nature that letting off steam usually results in training sessions evolving into mini-contests.
"Lewis is unbelievably competitive with himself and with everyone else," says Green. "We're a pretty different build so for things like chin-ups, for example, he'll beat me every time. But I can beat him at other stuff."
For both men there is no such thing as a typical week but they work constantly towards the same goal - the world championship - and do everything in their combined power to make that possible.
The healthy competitiveness extends to Hamilton's teammate. Green and Button's trainer, Mike Collier, swap tips on the best training methods but they also keep their distance when it comes to the finer points of their drivers' training.
"There's a great team ethic at McLaren and everyone's working for the same goal, but obviously Mikey and I have to make sure that we keep our data separate as that's private for the drivers, but we're certainly not averse to sharing the odd idea with each other."
So which of the two is fittest? Green's not saying, but suffice to say he is confident that, at the Abu Dhabi Grand Prix, Hamilton and Button will be the fittest men on the grid.