You could be forgiven for thinking that Jackson Williams took a few punches too many from Amir Khan in his final professional fight, for Williams then ran more than 3000 miles across the USA for his next sporting challenge.

You could be forgiven for thinking that Jackson Williams took a few punches too many from Amir Khan in his final professional fight, for Williams then ran more than 3000 miles across the USA for his next sporting challenge.

But the Norwich sports science teacher retains all his marbles. He gave up boxing after having been stopped in the third round of their six-round contest, and now has ambitions to run right round the world. He reckons it will take a couple of years to put plans in place, so meanwhile, as part of his training programme, he sets off a week today to run from John o'Groats to Land's End. During the Scottish leg he will don the vest he plans to wear in September, when he contests the freshnlow Great Scottish Run.

Last year, he ran across the US, from Los Angeles to New York, 3086 miles in 95 days, on 90 of which he ran. He and his team lived in a motor home as they crossed the continent, "We lost three days when it conked out, but the whole thing was tough. It was like Big Brother," he recalled. "It was hard. In some ways it was the worst stretch of my life. Living with four other people in a recreational vehicle like that wasn't nice."

He suffered more than 100 blisters, and says he might not have made it but for the retired doctor who accompanied him and massaged him for five weeks. "After treating my feet with surgical spirit in the second half of the run, they really hardened up, and I hardly got another blister.

"Mornings were the worst. I was up at 7am, fed and on the road by 8.0. But sometimes it would take two hours to cover 10 miles. I could barely get moving. The aim was to run 10-mile stints, but the first was always the hardest. I'd eat every 10 miles. I had to get down between 5000 and 7000 calories a day, and went through six pairs of shoes."

He started out aiming to run 32 miles a day with every fourth day off. "But once I got into the way of it, I felt more confident and switched to 40 a day for three days, 20 on the fourth, and then 40 for three days."

He missed the first birthday of his daughter, Poppy, but held up a card, designed on notepaper, a photo of which was emailed home.

Williams planned the whole trip, logistics, everything, himself, but aims to put something very much more structured in place for his global run. "I'd like to try to make a career of this," he says, and aims to consult Willie Sichel, the Orkney-based ultra runner. Sichel won the international six-day race which ended in Hamm last weekend, completing more than 20 marathons, but leaving him a tantalising 14 miles short of the Scottish record of 546 miles dating back to 1882.

Williams began his sporting career as a boxer, aged nine. He reached two junior ABA finals, one NABC final, and a youth ABA semi, but never won a title. In one ABA final he lost to Steve Birch, who won Commonwealth Games silver in 2006.

Williams had nearly 50 amateur fights and won around 40. As a pro he won 12 of 16 contests. The only time he boxed in Scotland was at Aberdeen's Beach Ballroom, where he met Lee McAllister. The referee stopped it in the fifth. "There were 1000 Scots cheering against me," he recalled.

Those who exhorted his rival might have been more sympathetic had they known Williams's mum, Maureen, is from Bargeddie, in Glasgow. "Yes, I'm half Scottish," he says.

He has secured a number of sponsorships, including shoe firm Mizuno. He also organised a dinner, which his erstwhile rival Khan turned up to support, as guest of honour.

"When I passed through Las Vegas, I was able to meet up with Ricky Hatton and Wayne Rooney. I'd never have managed that without the entree that boxing has given me, and if I had not fought Amir Khan.

"I genuinely thought that I could beat him, but it was not to be."

Jackson, from Norwich, says he hopes to complete the 837-mile challenge in around 14 days. "Initially, I hoped to try for the world record, which currently stands at nine days and two hours, but I haven't covered as many training miles as I'd have liked."

He has been running since the age of 17 has already spent 24 hours running on a treadmill in a Norwich shopping mall and eight hours on treadmill in the window of Greaves, the Glasgow sports shop, to raise awareness for the attempt.

"I'm a realist," he says, " and I understand the importance of mental strength and having the ability to narrow my mind's eye into tunnel vision when competing. I've been seeing a psychologist to help me prepare for my challenges."

Bryan Gunn, the former Scotland and Norwich City goalkeeper, is a close mate. Gunn lost his two-year-old daughter, Francesca, to leukaemia in 1992. "Bryan set up a leukaemia appeal, the Dove Trust, and I have run for that.

"I'm doing John o' Groats to Land's End for MEND, the children's obesity charity."

And if the Big Brother aspect of trans-USA wasn't tough enough, he will be slumming it this time. "We plan to live in tents," he says.