I shouldn't be writing this. Frank Baron, the photographer, should. He was there at White Hart Lane that night in September 1991 when at the end of their middleweight world title fight, Michael Watson was battered by Chris Eubank, collapsed and almost died. Watson had a blood clot on the brain, spent more than a month in a coma and, over the next few years, had to learn to walk and talk again.

By a neat circularity, Baron - who witnessed the chaos in 1991 from a gantry high above the ring - is back today to photograph Watson again. It's a touching moment and Watson comes vibrantly to life in front of the camera, striking boxing poses. He is in the middle of a hotel entrance, blocking a cab. The driver winds down the window and I anticipate a volley of abuse, but the cabbie smiles and says "How yer doing, Michael?" A fan who remembers. They shake hands, in that athlete's way that is more like arm wrestling, and have their picture taken together. Apparently, this happens a lot to Watson, who, denied the world championship by the blood clot, likes to call himself the "people's champion".

Watson is 39 now, in far better shape than he was in the early 90s when he was learning to talk again, taking his first tentative footsteps and battling depression. But his left side is still weak, his hand partially paralysed, and he speaks slowly and tires easily, the strain of giving an interview evident. When he walks, he sometimes needs a friend's shoulder to lean on. Today that friend is Lennard Ballack, who also prompts Watson occasionally when his memory falters. "But don't mention me," says Ballack. "It's Michael who deserves all the credit."

Watson's autobiography, The Biggest Fight, is published next week, a self-consciously inspirational text that celebrates his recovery. On the surface, the timing is odd: 13 years after the fight that almost destroyed him, a generation in boxing terms. But the book is the culmination of 12 months in which Watson has remade himself as a public figure: completing the London marathon in six days, and in the process raising £200,000 for the Brain and Spine Foundation; fronting campaigns for disabled sport and the Teenage Cancer Trust; and in January receiving the MBE. Watson's story has a happy ending.

He and Ballack laugh a lot, not least when I ask Watson whether he has a girlfriend. "It's complicated," he says, amid much guffawing. "I have friends. I just love enjoying life. I'm looking for a lady friend that is more serious. It will come in time." A prerequisite appears to be that she will have to have a strong belief in God - a central figure in the book and the first person thanked in the acknowledgments.

Watson's mother, Joan, a strong woman who has had to endure serious injuries to both her sons, is deeply religious. She belongs to a Pentecostal church in north London, and Watson has imbibed her devotion. "The main thing is, I've got God in my life," he says when enumerating all the positives that sustain him. He implies that God willed his "accident" (the term he prefers); that he was injured for a purpose; that he is a "vessel" for some greater good.

He is fond of maxims - "You can't correct the past, but you can correct the future" - but occasionally his guard slips. "I do a lot of crying deep in my self-being. I was brought up not to show my emotions, programmed not to break down in tears, but I do a lot of crying inside." Then he comes off the ropes. "But I thank God I'm alive. I still have dark moments, but they're not as bad as they were."

The dark moments in the years immediately after the accident were utterly bleak. "I got depressed in that period. I'm only human. All I can remember is being in that ring fighting for a world championship, then going blank and waking up in a hospital bed with a completely different body. My mind was all right, but my body wasn't. I was thinking, why are people looking at me as if I'm stupid?"

The fightback was slow: first, he regained eye movement, then his neck, then his voice and, eventually, his limbs. "I couldn't climb the stairs, so I had a lift built in my house. I eventually took a chance by taking a few steps on my own. I had some feeling in my legs and from there things came together. It took months of hard work. When I went back home and was with my friends again, I began to feel that I'd found my identity. I became myself again. Just getting up and making my own breakfast gave me my self-esteem back."

Watson lives alone in Chingford, with support from carers, but spends a lot of time in his mother's neighbourhood in Hackney, where he is a local celebrity. "People see him in the street and stop their cars to come and shake his hand," says Ballack. "That causes a jam and other drivers start hooting. It's chaos."

He has two teenage daughters, though they live with their mother and he doesn't see them as often as he would like. His own father, too, had been an absentee: God and the gym were Watson's mentors. "Boxing made me who I am," he says (this without irony, though boxing could also be said to have unmade him).

He believes the sport's professional bodies need to do more in terms of safety provision. Watson sued the British Boxing Board of Control for not providing adequate medical care at the ringside and, after a 10-year battle, is now in the final stages of receiving a settlement. But one person he doesn't blame is Eubank. "The biggest thing was to face reality and not to have any animosity," he says. "It could have happened either way. There was no intention on anyone's part."

It was in the 11th round that he was floored by a ferocious right from Eubank. Watson's neck jerked against the ropes as he crumpled and that is when the life-threatening damage may have occurred. Still, he emerged for the final round. The referee only intervened when it was clear he was incapable of defending himself. He refuses to blame boxing and has no desire to see it banned, though he accepts that radical reforms - headguards, shorter rounds, shorter fights - may be necessary before it can be deemed safe.

Watson rarely goes to fights these days - he evidently thinks it a pale shadow of the golden age of which he was part - but nor has he turned his back on it completely, making the occasional celebrity appearance. "I miss boxing; boxing misses me," he says. "But I have no animosity, no regrets. I've still got a life and I'm still enjoying it. I've still got a sense of humour and I love the people around me. I can walk and I can talk, and for four or five years I couldn't do either."

And with that he goes outside to have his picture taken, flattered by the curiosity of passers-by, throwing a few right hooks, looking pleased as punch to be standing upright in the weak sunshine.

· The Biggest Fight is published by Time Warner, priced £16.99.