Two years ago I was training for an ultra marathon. The race was 80km long and took us through Paris. But despite being in the middle of a major city, it was 90% trail.

Up until signing up for that race, I hadn’t done much running that wasn’t on concrete. I knew I’d have to swap my road shoes for something a little more grippy and build up my mileage on the trails, but I live in London so the second part seemed easier said than done.

But thinking back to the race description – 80km, 90% trail, through Paris – if the race organisers could find that much dirt in a big city, then surely I could too.

I was living in Zone 2 but close to Hampstead Heath at the time, so getting in some time on the trails at the weekend was easy. There’s dirt paths criss-crossing the heath and in the summer I lead my running groups on some of them. There’s also a parkrun there on a Saturday morning.

But during the week I was logging a lot of my miles on my commute going to and from my, then, office. So I had to be a little more imaginative with my routes.

As a commuter we often think of the fastest way to get between two points and the most direct route. But once you’re running and trying to build extra miles into your week, you’ve got more freedom to explore more interesting routes. And for me this meant finding less even ground to run over.

While I wasn’t able to find a door-to-door route that was completely trail (running through people’s back gardens might be the only way to do that), I took detours through London parks where I shunned the tarmac paths for the grass as much as possible.

Hardcore trail runners who are lucky to have peaks and dales as their playground might scoff at my soft southern trail running, but I took what I could get and I fitted it in wherever I could.

I moved house shortly after finishing that 80k race (it went well thanks – full report here) but I kept looking for trails where I could. I still live in Zone 2 but found that I could follow the New River for almost 2.5 miles to my office before it disappeared underground and I had to do the rest of the journey on concrete.

I can follow that river for a mile in the opposite direction to take the longer route to Finsbury Park, where I can run round the edge on the grass before following the Parklands Trail a couple of miles up to Highgate Woods, then either turn right up to Ally Pally or left to Hampstead Heath.

I can run a half marathon distance loop from my flat, along the river path and canal paths, then through Victoria Park and only have to do 3 or 4 miles on concrete, battling traffic.

The challenge I signed up for two years ago was to see if I could run for 80km. But that race keeps on giving as I keep challenging myself to find new paths to run on.