I talk a lot about battling and miltary stuff. Not because I like conflict necessarily, I'm just interested in that kind of thing.

You may well not be interested in what I'm about to tell you. If it's bikes you're looking for then you can safely skip this one and not miss a lot.

From the minute I woke up this morning, I knew that today was one of those days when I'd have to battle. Living with mental illness is like that sometimes. Sometimes you just have to grit your teeth and shove as hard as you can.

It feels a lot like the feeling you get when you're terrified of something. Maybe, for you, it's spiders or heights or something like that - but there is something which just causes you to be paralysed with fear. You know that feeling in your stomach? It all goes really really tight? Your heart starts to race, the hairs on the back of your neck stand up.

It's like being out in the dark and you suddenly get that feeling that you're being followed. You look round, but nobody's there. But you know, you just know, that you're being followed. You've got this heightened sense of awareness, your eyes flit from side to side trying to pick up every bit of movement - any clue which might back up this hunch that you have.

And all the while, you're gripped by fear. Physically paralysed by it. It's taking all of your energy, and all of your concentration. Sometimes, about every five minutes or so, you take this really sharp intake of breath and you wince in pain - it's like you've just been punched in the stomach. There's no reason for it, at least none that you can figure out.

You go out to get a cup of coffee. There's a couple of people walking towards you. Are they going to attack you? It certainly feels like it. They might be. Should you attack them first, to make sure that you keep the advantage? They're looking at you. Are they looking at you because you're looking at them? Or are they looking at you because they mean to do you harm? What's the right thing to do? Do you run away and avoid a fight, or do you march towards them like you're looking for one?

And, as if this lot wasn't enough, you have to get through the day at work in the same way you did last week - when you were feeling better and nothing was a problem. You're on your toes the whole time - afraid, alert, distraught - and just wanting it to please stop.

This is doing battle. This crap, which grips me and paralyses me and tortures me about once a month, is what gives me the balls and the stamina and the determination to make it round an enduro course. Three hours through cowshit is a walk in the park compared to the physical and mental effort it takes to get through a Bad Day In The Life of a Manic Depressive. Even if Martin is hiding behind bushes to pass you twice inside 10 minutes and wind you up.

Today is one of those "break glass" days. One of those days when you reach for the medication since it's the only way you're going to get to sleep. As much as I detest the medication, and am ashamed of having to take it sometimes, the alternative is even worse. The alternative is that you lie in bed savaging yourself with your thoughts - you physically wince and recoil at the pain.

And there is no way out. Well, actually, there is - but it's not a realistic option for me. It is for some people, who get pushed further than they can take.

I went to school with a guy called Chris. Brilliant guy. A lot of people thought he was a bit odd, but he was a great guy. This guy could throw a cricket ball nearly 100 metres. That's 100 metres through the air before it landed metres. And he could climb. He loved climbing. He was a gifted cyclist, and could easily knock out a couple of hundred miles in a day. And he was my friend.

My Physics teacher, one of the best climbers in the UK, used to take us climbing. Sometimes, he'd do this instead of teaching us Physics. When we went out, he'd just let Chris and loose with a couple of harnesses and some rope and a vague instruction about where and when we were to rendezvous. Here's us - couple of 14 year olds - climbing up and down the harsh cliffs of the Cairngorms unsupervised. Not a social worker or Health and Safety guy in sight.

Anyway, Chris suffered from depression. Badly. His elder brother had hung himself when Chris was 8, and this really affected him.

One day, he went up Arthur's Seat in Edinburgh - an extinct volcano - to a place called Salisbury Crags. These are steep and sharp cliffs that run round the side of the hill - couple of hundred feet high. Great climbing. Anyway, he walked to the edge and dived off head first - couple of hundred feet head first into the boulders and scree.

This is what depression can do to you, and - even though you may never be able to get your head around it - it can actually seem like the most sensible thing to do at the time.

This is doing battle. This is my life. For all its trauma, harship, injury, exertion and effort, enduro is nothing compared to this battle that I have to fight every month. They can't do anything for me, any more than they could make me a foot taller. I need to live with it and - more importantly - be able to deal with it.

I will emerge from it in a day or two, and will be stronger for having done it. Please bear with me - we'll get back to bikes shortly.

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