Next Sunday Steve Davies will get out of bed on the wrong side. When he puts on his shoes, he’ll make sure it’s the left foot first. Alison Richards, meanwhile, will be eating her “lucky” breakfast of banana and honey on toast. Such are the rituals of the long-distance runner. Then, with 30,000 others, both will head for Greenwich to run in this year’s Flora London Marathon.

Neither 35-year-old Steve, deputy head of Grinling Gibbons primary in south London, nor 24-year-old Alison, a PGCE student at Sheffield University, has a chance of winning the pound;35,000 awarded to the first man and the first woman home. But each has entered this l9th marathon with definite goals: Steve wants to get home within four hours, Alison to beat her 1997 placing of 348th.

They’ll be among 1,800 teachers - one of the biggest professional groups in the event - who juggle hours of training with work. What drives them to push their bodies to the limit?

Mike Vassiliou, osteopath and veteran of three marathons, claims the 26.2 mile outing, which is the biggest running challenge most non-athletes could possibly face, can give you a “fantastic high”. But he warns: “Marathons become your life. They eat into social time, work time; they enter your every thought. You’ll be sitting in your office and all you can think of is the 10-mile run you have to do that night.”

Both Steve and Alison have sporting pedigrees. Steve is a former professional footballer who’s been teaching for 10 years; Alison is a cross-country veteran. But both say fitness levels are relatively unimportant when you start training - mental commitment is what counts.

For Steve this has meant a series of 5am starts, fitting in a run before school. And he knows he will find the marathon hell. He gets round the course, and through the pain, by visualising landmarks on the route and focusing on the places he knows friends and family will be waiting to cheer him on.

The pain? In marathon-speak this means “hitting the wall”, the point when your body exhausts its store of carbohydrates and starts to burn fat. In Steve’s first marathon it felt like an adventure gone wrong. “At 15 miles I suddenly thought the whole thing was barbaric. My mind and legs felt like they were exploding. It was the longest four hours and 40 minutes of my life.”

Alison says she didn’t hit the wall last time out but admits she can “hardly remember” the last four miles, when “all I wanted to do was stop”.

Steve reckons part of his problem is that he’s built for sports other than marathons. “I’ve got footballers’ legs,” he points out - a polite way of saying they’re not spindly.

Mike Vassiliou agrees that not everyone is naturally suited to running marathons. “The ideal shape is thin, biometrically symmetrical (legs the same length) and with large heart and lungs. But if you’re not built like this, don’t let it stop you. Just be aware of it.”

Steve runs most mornings and some lunchtimes, although he “saves” the big distances for the weekends. Alison admits she is not a morning person. She runs when she gets in from her course, and a month ago was struggling. “Training really has fallen off in the past couple of weeks as I’m in the middle of a big block of teaching practice and my weekends are taken up with a games course.

“I have to be really strict with myself when I get home. If I sit down for 10 minutes, I’ve had it.”

Mike Vassiliou says training for a marathon is all about preparation, and being aware that no programme can be set in stone - body shapes and types are too varied. Incorrect training is a recipe for injury, he says. If you are in pain, stop; it’s the body’s message that something is wrong. Keep going and you could suffer serious injuries.

Steve Davies broke this cardinal rule in his second marathon. He hobbled the last five miles with a split calf muscle, then spent the next six weeks in plaster. He admits it was a daft thing to do but the “sheer agony” of giving up, knowing he’d done 21 miles with only five to go would have been worse than any physical pain.

There’s a technique to running correctly too. Novices tend to run on their toes, which can cause stress fractures of the shin. Mike advises any marathon hopeful to start with a 10km race or a half-marathon, giving the muscles a chance to get used to sustained effort.

He has no plans to run another marathon himself. His last outing included going up and down Mount Snowdon , and he says he’ll never forget the pain at the finish: “It was worse coming down than going up. I decided that was it.” But he’s still a fan. “A marathon allows you to focus your thoughts, and to fulfil a potential you didn’t know you had,” he says.

Steve says anyone who claims to enjoy running a marathon is “a champion or a liar”. But then he admits: “I love being on that start line. It’s inspirational.”

Flora London Marathon, Sunday April 18. Start times at three Greenwich points are: 9am (elite women), 9.15 (wheelchair athletes), 9.30 (rest of the pack, including elite men). Details of next year’s race from Flora London Marathon, PO Box 1234, London SE1 8RZ. Tel:0171 620 4117. Website: www.london-marathon. co.uk.Hotline for this year’s race:09068 334450