It's a cruel twist of fate that a man who has pushed his body to the limits of human endurance should find that the greatest struggle he has ever faced is with his mind. Such is the plight of double Olympic rowing gold medallist and extreme adventurer, James Cracknell, as documented in the first instalment of a new series of Life Stories (ITV4, Tuesday).
Hit in the back of the head by the wing mirror of a truck at 70mph somewhere in the American desert, it was first thought he might not survive, then that he might not recognise his wife Beverley; in fact it was she who struggled to recognise him, in terms of the changes to his character, and she still does to this day. "I woke up and I knew who she was," he admits, "but I wasn't the same person."
So the man who always strove to do more, for longer and quicker, must now wait and hope that there is some improvement, a chink of light to show through the cracks. But his other half remains strong; she has put up with more than most – more than almost anyone since the days of Scott and Shackleton, in fact – and was viciously attacked by Cracknell at one stage.
Without a trace of humour she says: "There's a lot about the old James that I wasn't very keen on, to be honest." It's a stunning comment but you see the positivity behind the anxiety and catch a glimpse of the powerful support network that has allowed this big boy who never grew up to pursue his madcap dreams.
Cracknell is interviewed in a bare room in a bad state of disrepair. No doubt this was someone's idea of a meaningful conceit but it seems unduly harsh in an otherwise sensitive production as he sits in a lonely chair holding his head in his hands. But we also see him standing peacefully by a river, holding his gold medals as he relates his pride at seeing one of his kids watching the London Olympics with those medals hung around his neck.
He also reveals why he took up rowing: "What got me there was a dislike of cricket." He was fielding on the boundary by a river when a boat went past propelled by a team in perfect unison, while on the cricket field one boy was hogging all the attention while the rest stood around watching. One can only imagine how different things might have been if he had pursued cricket with his relentless enthusiasm; the Aussies might not have won all those Ashes series during the 1990s.
His guru Sir Steven Redgrave admits Cracknell pushed his coxless four team-mates so hard that he was a major part of the reason they achieved their success. Yet he is not the ideal team man. "That's his weakness perhaps, that he can push himself and ignore everything around him," says Redgrave.
Nor is Cracknell a real Olympian like the five-time gold medallist; he did the rowing because it was a challenge, and then he moved on – too soon, according to Redgrave, who believes his switch to endurance racing might have caused his accident.
So Cracknell rowed across the Atlantic, trekked to the South Pole and became the fastest Briton to complete the Marathon des Sables – seven marathons in the Sahara desert in six days. These are essentially lonely pursuits – man against the elements – and single-minded tests of character.
Now he has chosen a radically different ambition, even by his standards: to be elected as Member of the European Parliament for the Conservatives. It's a decision which might make him seem an even more alien species to the rest of us. And it might prove to be his toughest challenge yet as he tries to scale the twin brick walls of Tories scepticism and EU bureaucracy. Perhaps this time he really is going too far.