By day Kathryn Hearn, 36, is glued to her computer.

By night, she is glued to the television.

In between she eats.

China Diary Week 2: 21/1/03
So why has the unfit, mother-of-two (yes there is a comma) signed up to a challenging trek for the Meningitis Research Foundation along the Great Wall of China?

I’ve done some terrible things while drunk and on the Internet. Once I contacted all the people I ever knew from school via Friends Reunited emailing them with goodness knows what rubbish. Another time I bought 10 pairs of trousers in a sale.

Signing up to trek along the Great Wall of China is another thing I can add to that list. I wasn’t actually drunk through alcohol though. I was inebriated with the spirit of New Year and resolutions and all things philanthropic.

So now I am into the second week of my challenge and I still can’t really believe what I have chosen to do.

No sooner had I uploaded last week’s diary than I started to look more closely at the trek information. The picture on brochure’s front shows a precipitous cliff that looks more dangerous than I’d ever imagined: "This surely has to be the Andes challenge," I implored my colleagues, as we pored over the picture to make out any national landmarks.

I’d almost scrubbed this image out of my head until last night I received an itinerary for a similar Great Wall charity trek, which includes these terrifying words:

"Day Five: We start our day’s walk heading up the steep renovated steps towards what appears to be a sheer cliff face. This is where we encounter "Heaven’s Ladder", a vertical climb of over 200 steps leading us up the cliff face."

I once climbed to nearly the top of Snowdon. I fell over 16 times (my husband counted them) and cried when some enthusiastic German we were with suggested reaching the peak. Some people don’t do red meat. I don’t do cliffs.

This itinerary also includes a very vigorous 16-week training programme to prepare you for your trek. This stipulates four consecutive days of walking six or seven miles – are they completely mad? Do they not realise I have a life to fit in, plus with all my additional exercise I have literally loads more of washing to do.

What I’ve been wondering while on the treadmill this week is, how many pairs of jogging bottoms does Paula Radcliffe have? One in the wash, one spare, one sweaty?

Roll your mouse over Paula Radcliffe to see how our training compares

I have actually got a new pair of jogging bottoms purchased I think in way of a hint by my husband for Christmas (It was the sports bag and running top that gave it away). They are incredible because they have little zips by the ankles, which are really handy for …. Perhaps if your ankles get overheated they can vent them?

On the subject of kit I had an enlightening experience this week at the gym. I was contemplating the fact that, being new to the effects of sweating in the gym, I had forgotten to pack alternative underwear and was left to go home pant-less.

But looking around me I realised that most of the other women were underwearless underneath their Lycra get-ups! Is this normal? I might start up a message board on the subject: pants while you pant? But then again that might get this site into further trouble after Olly's lap dancing feature . . . I’ll stick to making a mental survey of this phenomenon.

I’ve managed to get pretty average on the treadmill. Mostly this has been by diverting my mind away through the horrors of my flesh slapping around and my heart pounding by imagining my own fitness video. I’ve compiled a possible list of titles, although at the moment I am veering towards an original name, Kathryn’s Urban Sprawl.

It would include a mixture of all types of music, as long as the songs are short, and definitely no Fat Boy Slim music as I’ve been to one of his concerts and, call me old and past it, but it’s impossible to know when one song (track/whatever) ends and another starts.

Just when I thought I was getting even with my fitness, I face another setback. My overwhelming desire to trounce the treadmill is being hampered by work commitments.

I would get out of seeing Nigel Havers in Art at Milton Keynes Theatre tonight and then seeing Matthew Bourne’s The Nutcracker at a press showing at Saddlers Wells on Wednesday, because OBVIOUSLY I WOULD RATHER BE IN THE GYM than enduring these theatrical treats, but someone has to do it (And if you heard Katy’s Electric Sheep interview with Nigel she definitely needs chaperoning to the theatre).

On a related subject … French Kiss, the film, was on TV this weekend and Meg Ryan plays an aeroplane phobic. This brought back into clear vision my last flight on a place, from Majorca, where I vowed never to get on another aircraft again.

I remembered shaking with fear as I complaining about the disturbing noise coming from the emergency exit door.

Then complaining again, this time a little more assertively, and asking what exactly was wrong that the door was vibrating so much and making a pig-like squeal.

And then refusing the air steward’s kind offer of moving seat, since if the emergency door is going to fly off, it’s pretty pointless to be two rows nearer the cockpit. And then seeing impending doom and crashes ahead as my six-year-old son asked me which was better, to crash on land or sea as he examined the safety instructions with fascinated glee.

So obviously three months later I sign up to fly 5,000 miles. Then on Monday they announce that, for the first time in years, the number of deaths in aircraft crashes has gone up. So that’s all fine and dandy.

Oh yes. I need a whole heap of injections too. Just call me Mrs Happy Bunny. I still have yet to receive official confirmation that the trip is on – and that’s strangely reassuring for me at the moment.

But I went to visit Hannah, my friend’s daughter who had meningitis, and all the details that I am worrying about seemed irrelevant. It would really be something to raise that amount of money for Meningitis Research Foundation - and would help so many.

And that’s what I’ll be thinking about this week as I tread the treadmill, looking out for visible panty lines in the gym.

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