It had to be done. You know how you start thinking about something and you think about it and you think about it until you realize that it's only a matter of time till you do it?

In the olden days it was sex and drugs and changing jobs and moving to London and worse.

More recently, it was boot camp.

Every time I walked the dogs in any park, I had to dodge dozens of panting grunting sweating middle-aged people in lycra doing push-ups and lunges and worse.

And there'd always be some drill sergeant type shouting 96! 97! 98! 99! 

Oh lord, I thought.

But now it's me.  There was no screaming "Move your lardass you pathetic snivelling worm!" but there may as well have been. The first time, I had to go to bed for the rest of the day. The second was torture. The third (despite press-ups on a ball and far too much sprinting) was just about tolerable.

Now I'm hooked.  And already I feel less like a pathetic snivelling worm.

In addition, this being North London, the whole enterprise is weirdly colourful in unexpected ways. Our drill sergeant type, for instance, is a small, insanely fit young woman with an incredibly well-developed imagination. She reports that she was once a member of Mossad, danced for the Barcelona ballet, raced on the Austrian national ski team, qualified for Olympic gymnastics and judo teams, went to Columbia medical school and has worked as a journalist, horse riding instructor, animal trainer, author, stockbroker and cordon bleu chef. Impressive.

Our spot on Highbury Fields is overlooked by Nick Hornby's kitchen and rumour has it that complaints have been registered about boot camp happening within eyeline.

That was before I joined the group. I noticed the other day they've installed black-out curtains.