Frankly, Tick Number 6 on my Ten Things Marathon List was a bit of a disaster.

It was typical me, really, with my customary lack of planning and last-minute preparation. Although I have got away with this before on my marathon adventures, I really was found out on the 4th May, the day of the Neolithic run from Avebury to Stonehenge.

I only made the final decision to tackle this cross-country marathon on the day before and thought that I could simply roll out of bed on the day and run my usual race. Big mistake.

The first inkling that I wasn't going to be quite up for it was prior to the start. The usual dyed-in-the-wool types were there as normal, including the by-now familiar smattering of 100 Marathon Club members. Something was different though. My shoes. How could I be so stupid? My well-travelled Asics were not built for mud and grass and stuff. They were strictly road shoes and a nervous look around at everybody elses' impressive off-road footwear made me realise my schoolboy error.

I tried to comfort myself with the notion that surely shoes weren't that different and probably a ploy by the good people of Nike et al to extract more of our hard-earned cash. But the absence of a pair of Multi Terrain Fourtrak Gravel Masters gnawed away at me during the early miles over mud, ruts and gravel and I knew that this was not going to be a good day at the office. Of course, the bigger reasons for a new Personal Worst were my poor preparation and my failure to take it easy at the start.

Bizarrely, I thought of the Slaughtered Lamb in "American Werewolf in London" as I walked-ran the last ten miles or so. "Keep off the moors! Stay on the roads, lads" the inner voices said. The warning had come a little late for me, but I think that it's safe to say that I will be back on the road for the last four marathons of the Ten Things 40 challenge..

My goal is to find and complete a total of ten marathons by the time I reach 40 in late September. The good news is that I'm now halfway through with five down, five to go and a whole five and a half months left to tick off the remainder of my personal list.

I freely admit that this is not a spectacular achievement and pales into insignificance when measured against true feats of athleticism. For instance, I am not running a marathon a day for seven days in different continents, nor am I climbing Everest or cycling from Lands End to John O'Groats dressed as a Giant Tomato. Maybe I can do one of these next year..!!

What makes this personal challenge a bit more, well, challenging is that I've left it so late and to achieve the goal will mean I will have run eight marathons within a 10-month period. I guess this makes it seem a bit tougher, particularly given my fairly hectic work schedule and the fund-raising for the Anthony Nolan Trust, which I hope will make the effort worthwhile.

Marathon Number 5 on my list was last Sunday - not London, but Tresco on the beautiful Isles of Scilly. This was a tough 26.2 mile jaunt with over 7 laps of the island necessary to make up the distance and some 28 hills to negotiate. I am a little undecided on the next marathon and think that this will be a little closer to home. Watch this space or visit the website www.tenthingsforty.co.uk for details.

You can follow the link from the website to my online giving page or directly at www.justgiving.com/stuartwickham All money raised will go towards helping the Anthony Nolan Trust's work in enabling bone marrow transplants to reclaim lives back from leukaemia.

This is something of a mid-life crisis thing and regular readers of the challenge website will know a little more about the motivation behind "10 Things..". In a nutshell, it relates to a goal I set myself at the time of my first marathon, London 1999.

I suppose it is typical me - the self-proclaimed Last Minute Man - to be posting my first blog entry for "10 Things to do Before You're 40" halfway through, but another case of so much to do, so little time.

However, I do hope that you will follow the story through to it's conclusion in September.