This man is about to run around the world. Five continents, 52 countries, 39,920 miles. It will take him four years at up to 60 miles a day. Is he mad?

Faith is buying a pounds 1 lottery ticket and being convinced you will win the jackpot. It is believing your 15-year-old dog - blind, cancerous and incontinent - will live for ever. Faith is taking your car to a main dealer, never expecting them to phone and say: "Ah, there's a bit of a problem with that one". It is believing in Father Christmas, politicians' promises, newspaper horoscopes, the dial on the side of your toaster. And faith is... Robert Garside.

An unassuming 28-year-old student, Garside sets off in December to run round the world alone. Yes, that is right. The full monty. Five continents, 52 countries. He reckons to cover almost 40,800 miles (the plane journeys between land masses don't count), and pad into Piccadilly Circus sometime around September 1999. It is a wildly ambitious project for even the most dedicated ultra-runner. Never mind the running: just think of the language problems, the mass of visas, the nutritional difficulties. Garside, however, has solved all these hurdles by the simple expedient of ignoring them.

Languages? "I'm not very good at languages, but I can probably get by in Slovakia." Visas? "When I get to the borders, I'm sure I'll be able to work something out." Food and water? "On high-mileage days I may carry a snack, such as a small orange or lemon, a banana and a small chocolate bar. In the evening I will eat a balanced meal." In Gabon, Senegal, Afghanistan or Western Sahara? But Garside is convinced that people's innate generosity, two years of a psychology course, and a letter from Nelson Mandela will see him through. This man has enough faith to make the Pope look like a heretic.

He became interested in running 10 years ago. "I got sick of doing the clubs and pubs, and decided to get fit. Running became an obsession. I ran 10 miles in the morning, 10 miles in the afternoon. I did a couple of marathons and was doing around 2 hours 30 minutes, but I didn't want to be just another marathon runner."

Inspiration came from The Guinness Book of Records. "I noticed that people had run some very long distances and that someone had even walked around the world but, when I checked, nobody had actually run it. So I decided to be the first." For the past year, he has been planning his route, running at least 20 miles a day and reading The SAS Survival Handbook ("I'm learning six pages a day").

On 20 December, he will leave Piccadilly Circus, run to Heathrow and board a plane for South Africa. If all goes well, Nelson Mandela will start his epic run - and that is when it starts to get tough.

In Africa alone, his route takes him through some of the hottest, poorest and wildest places in the world: Zaire, Benin, Togo, Mauritania - it is a daunting list, but Garside seems quite unperturbed. "The Foreign Office have given me a list of the countries like Angola and Congo I'm a bit uneasy of, but I think my two years of psychology will come in very useful. It's the study of common sense, like training a dog. It's very simple principles." He adds, as an afterthought: "And it's much harder to shoot a running person than someone who's walking."

Well, that should be a great consolation. But what about lions, buffaloes, elephants, leopards, snakes? "The best protection is by planning to avoid them. If it's practical to employ a temporary guide through high-risk areas, then I will. But I'll be sticking to the main roads anyway. In hot countries, I'll be eating plenty of garlic, which will help to keep mosquitoes away."

If (sorry, when) he gets through Africa (8,082 miles, 307 days) he will fly to Spain, and trot through Europe (3,950 miles, 194 days). In Slovakia, he will drop in on his parents, who have moved there from Cheshire, and collect some more words of wisdom from his mother. So far she has advised him: Do not think about the fame, think about the pain - which sounds like a Slovakian proverb.

After 53 days (1,187 miles) running through the Russian Federation, he crosses the border to Kazakhstan and spends 277 days crossing Asia (5,808 miles). The Himalayas includes the highest point of the trip, which Garside thinks is about 17,000 feet. Altitude problems? Not for our man. He will still be reeling off distances of up to 60 miles in a day, according to his schedule. Isn't that quite a lot, I venture? He seems surprised. "I've got 24 hours to complete that distance each day." Of course.

In Malaysia, he will rendezvous with his girlfriend, who appears to have distanced herself fairly effectively from Garside's project. But love will not delay him. He has built in only three rest days out of 22 in Malaysia (514 miles), Australia beckons, and a 2,393-mile slog from Perth to Sydney (114 days). It can get pretty hot in the middle of Oz come summer time, with temperatures as high as 50C. But Garside is not worried. "I've done a marathon in 38C," he says confidently. Well, it is only another 12 degrees.

He will probably be glad to get to Chile (geddit?) after that. Through Argentina, Peru, Ecuador, Colombia, Panama, Costa Rica and Mexico, getting ever nearer the United States and his dream of spending the night on an Indian reservation (don't ask me why.) In California, he plans to meet Dave Kunst, the first man to walk around the world, and swap stories - Kunst's brother was shot by bandits in Afghanistan, and Kunst himself only survived by sticking his finger in the hole made by a bullet.

It will be all downhill (figuratively speaking) from then on, and, once in New York, Garside plans to run up and down the Empire State Building to prove how good he feels. The last leg of the journey is from Glasgow to London. "I want to be back in England in time for the millennium," Garside says.

And that's it. A total of 39,920 miles, taking just under four years with 209 rest days, all with a backpack weighing less than 10lb. It will include letters from his local MP and The Guinness Book of Records, character references and sundry items including a "sceptic pencil", according to his equipment list.

You may think this article was written with one. You could be right. Perhaps I am being altogether too cynical. After all, his fearless but naive approach may be just the way to conquer the world (we've done it before that way, after all). And didn't a Briton sail across the Atlantic in a bathtub? No, now I think about it, he did not. The tub sank in Plymouth harbour.