I hope there are many regular readers of this column who are enjoying my stories of pain, physical torture and fatigue. This week however, I wanted to enlighten you all on some of the other sacrifices you have to make in preparation for the London Marathon. They will all be worthwhile but are something I, and therefore most readers, will probably not know.

Diet is the first thing. Those who know me are well aware that I like little more than a nice three course meal washed down by the odd glass of vin rouge, but as soon as you start training, you are told that most of that is not a good idea. It has proved difficult for me as I have to eat a certain amount of fatty foods - when you have cystic fibrosis, fat is a vital part of the daily intake of food. At first I also decided to give up alcohol - I went for six weeks without beer, wine or anything but have to admit I did lapse as I was finding it hard to relax. However, the focus has returned and I am going to stay 'clean' until April 18.

Then there is the financial sacrifice and it is one which I had not appreciated when I signed up for the marathon. As well as trying to raise £10,000 for charity, a lot of money goes on preparation and equipment - at the moment it runs to several hundred pounds. I have had to buy a £90 pair of specialist shoes, fees every time I use the leisure centre, running and reflective clothing, the extra needed for special food and £30 on a Camelbak, a special backpack for carrying water on long runs.

But I haven't got the hump because completing the marathon will contemplate all that.

And there is also the time sacrifice - the average training run takes an hour and a half every night with a swim or weights session doing the same. Doing that when you only have four hours spare every day is quite a slog.

I do not wish to harp on about my hardships, after all I was nuts enough to sign up for the marathon in the first place, just to give readers a full idea of what goes into preparing for this most unique challenge.

* If you would like to sponsor me or feature in this column, you can e-mail alansmarathon@ukonline.co.uk, visit my website at www.alansmarathon.ukonline.co.uk or send cheques payable to Alan Williams, c/o Mid Somerset Newspapers, Southover, Wells, Somerset Ba5 1UH