Ah, January: when the battle is on to lose all that extra weight you put on at Christmas.

This year I have taken to locking myself in a darkened room.

Well, not a room exactly. It’s a shed without a light.

You see, in recent years I have come to the conclusion that the best way for a man of my age to fight the perpetual fight against middle-aged spread is to get on yer bike.

Generally it works, and for most of the year it isn’t so much a chore as a pleasure, because I actually enjoy cycling (you should try it).

But not at this time of year, when it’s cold and - more to the point - dangerous.

Not only is January dark more than it’s light, but even the light bits are dark if you count the murky days, which is most of them.

And if that isn’t enough to sort you out, the wind, rain and ice will.

So this year I am experimenting with a new way of staying fit without having to venture out so much, apart from walking down to the shed in the back garden.

In there I have set up an old bike on a device that serious cyclists call a ‘turbo trainer’, but which I tend to call ‘the roller thingy’.

The back of the bike is held off the ground so the wheel sits on a small roller, while the front wheel rests in a plastic tray that holds it still.

You can set the resistance of the roller, and there are five levels of difficulty.

The lowest is like cycling on the flat, the next one is about the same as going up a moderate hill, and the third is like going up a big hill.

I can only assume the fourth is like Everest, and the fifth must be for people who like to cycle vertically.

I only use the bottom two settings.

That is quite enough to make you sweat like a pig, which I suppose is the object of the exercise, and challenging enough.

However, the hardest thing is not the pedalling, but the boredom.

In fact, you don’t know the meaning of the word ‘boring’ until you have tried pedalling for three-quarters of an hour while staring at the inside of a shed door.

These days it is possible to hook your bike up to a screen that will simulate actual rides, including in exotic places, but not if you don’t have electricity laid on in your shed, and loads of cash.

So I have to come up with my own ways of relieving the boredom, which so far has meant listening to music through headphones.

This might sound like a good solution, but the problem is it is impossible to cycle at any tempo apart from the one in the song you are listening to, and you can’t keep stopping and starting to change the album.

So you either end up cycling too fast or too slow.

My wife suggested I should try listening to one of her favourites, Phil Collins, because he is pretty steady and middle-of-the-road.

But I tried that for a few minutes and decided that - sorry, Phil - that’s even worse than staring at the door.

“It’s no good,” I told her. “I need to come up with something to make it more interesting.”

She thought for a while and said: “Well, you could always do it naked.”

Anything is worth a try, so I will leave you with the disturbing thought that the phrase ‘something nasty in the woodshed’ just took on a whole new meaning.