Self-confessed couch potato Rob Liddle has just six weeks until he takes part in the London Marathon. The pace is starting to tell. Will he stay the course?

There are six weeks to go until marathon day, and the dreams have started.

I'm in school assembly and the headmaster is detailing the arrangements for next week's final exam in a subject which, either through misunderstanding or laziness, I haven't studied for the previous six years.

The trouble is that it's never so close to the exam that I can just write it off - I'm left with the impression that, if I crammed all day and all night, I might still scrape a pass.

The dream scene switches to the school playing fields and I'm explaining to the gym teacher that I can't take part in the cross country run because I've forgotten my kit.

"You know the rules, Liddle," he says through clenched teeth. "Underpants!"

New record

Fear of public humiliation in my marathon attempt is a powerful driving force, but what's the worst that can happen?

I haven't yet told my osteopath, whose parting shot when she signed me off six months ago was: "Now remember, no more running" First instalment of Rob's diary

I suppose I wouldn't like to feel that, even if I complete the course on 18 April, I hadn't given it my best shot.

So, since my last bulletin, I've been trying to take the challenge more seriously, aiming to do a short session every other day, with one long run at the weekend.

An infection acquired via my daughter's nursery resulting in a chesty cough meant I wasn't able to hit the streets for two weeks, but I think I managed to tide things over on the gym treadmill.

And Sunday saw my greatest achievement yet, a ten-mile run - 15 circuits of the park -without recourse to walking.

It took me an hour and three-quarters and it's left me so stiff that I'm doing a passable impression of C3PO, but my back's holding up so I'm pretty happy.

I just need to put three of those runs together, end to end, and I'm home and dry.

Fancy dress

Annoyingly, I still haven't lost any weight as a result of stepping up my exercise regime, but this doesn't stop my workmates telling me that I have. No, I'm afraid all the fat hasn't "turned to muscle".

Some of them, over the lunchtime pint, have encouraged me to don a comedy costume on race day.

While this would undoubtedly make the experience even more uncomfortable, it has the appeal that the focus is removed from the time it takes you to complete the course - the fact that you get round in your antique diving suit is enough.