One of the trickiest things about living in a big city is preventing your kids from turning into hopeless couch potatoes. Heavy urban environments like London are just not designed with children in mind - and those spaces that do try to cater for them always seem to get spoiled by a thankless, careless minority.
I would never let my children go to the park alone in our rather shabby corner of West London - and believe me, I am not an overprotective mother. But although the council has spent millions on sprucing up our local playground, there always seems to be some grinning, tattooed yob peeing down the slides or stubbing out his cigarettes in the sandpit.
The result is that most children don't really get outside much unless they have their parents with them. So if you want them to exercise, you have to get involved.
I'm lucky in that I have one incredibly sporty child, my son, who when he isn't thinking about, watching or discussing football, is playing it with his local junior league squad. My daughter, by contrast, could not be less interested in any of the activities that, over the years, I have enthusiastically and expensively signed her up for.
Tennis, hockey, ballet… nothing has really stuck. I was beginning to despair of her ever getting hooked on exercise, when I hit upon an idea: mother and daughter training.
So now, while her little brother races around a football pitch for two hours on a Saturday morning, she and I head for a discreet corner of Hyde Park where we are joined by the long-suffering Olly, our personal trainer.
Since both of us share a hopelessly short attention span, we do interval training, which seems to suit both our temperaments perfectly. Like me, my daughter is quite strong and flexible, and she absolutely loves strapping on her boxing gloves and pummelling the hell out of poor Olly. "I'm imagining you're the school bully!" she shouts, as she delivers another uppercut, before taking a running kick at him.
We skip, we do step, we lift weights, do plank, leg lifts - the lot. And it's really good fun. But perhaps most importantly of all, it's special, something she and I do together, a unique shared experience. It also helps her talk about her problems at school (as any parent of a Year 6 child knows, it's a tricky time) and vent some of her frustrations.
Best of all, it doesn't feel like a chore. I'm not nagging her, and she's not feeling put upon. It is a genuine bit of mother/daughter bonding. Which makes our post-workout mug of steaming hot chocolate all the more delicious.