In my experience, running can present all manner of difficulties and decisions.

When to fit it in. How far to run. Where to run. Alone or in a group. And what can be carried along the way (iPhones and running shorts don’t mix, I find.)

I can’t stand gyms. Each to their own, but I don’t find it fun to run for several miles whilst staring at the same dull view of other gym equipment and generally fitter, sleeker members, whose limitless energy saps your own motivation.

I like to feel that I’m actually travelling somewhere, that there’s some kind of purpose to the distance that I’m travelling. When I lived in Hereford, I used to walk five minutes to the racecourse, the perimeter of which forms a 1.5 mile circle, ideal for running on. And within the racecourse is an athletics circuit. Twice around the racecourse (on a good day), followed by four circuits of the athletics track. (I never said I was a long distance runner – four miles is about my limit!)

Now that I’m in Cornwall, there’s a conspicuous lack of racecourses. And flat routes. But no matter. I’ve found a perfect place to run, which is level, easy to get to, quiet, and forms a there-and-back-again four-mile run. And what’s more, it’s a beautiful route and full of wildlife.

Years ago, Kings Wood, south of St Austell, was somewhere we’d go for a Sunday afternoon walk. Then, after I moved upcountry, someone had the idea of widening the riverside path into a cycle route. These days, the Pentewan Valley is a hugely popular cycling route, leading to The Lost Gardens of Heligan at one end, and into the heart of St Austell at the other, linking eventually with the various Clay Country trails.

An evening run between London Apprentice and Pentewan (and back) is a four-mile thing of joy. The route itself switches from track to woodland to riverside to woodland to village, providing some variety in itself. The St Austell River (or the White River as it was known then, due to the china clay deposits that would turn the water milky white) trickles contentedly between the trail and the Mevagissey road, its banks lined at present with red campions and buttercups and so many wild plants that I can’t name. Mallards are usually spotted about halfway down. On one occasion, about four weeks ago as dusk was falling, my footsteps disturbed a grey heron, which I otherwise would have passed, oblivious. It flew off, further ahead of me, but I saw enough to marvel again at the size and utter silence of the creature.

Further along, where the trail re-enters woodland, the feeling is very different. In the evening time, when I run, the trees are ringing with the calls of countless small birds, and blackbirds rippling through complex melodies. And all the while, a different type of watercourse lies to the right hand side. Much more still, than the “babbling brook”, this water is more reminiscent of a swamp. Tangles of trees and shrubs fight for space amongst the water and you really feel that any kind of creature could be lurking just out of sight, and that if you strayed too far into the undergrowth you could get an unpleasant surprise. So you glance ahead again, or to the left, and smile at the ordinariness of the robins and woodpigeons, which don’t seem to care whether you’re there or not.

And the last time I went for a run, well, I pulled a muscle. But that’s not the important part. As I ran through the woodland at the Pentewan end, I saw, up ahead, a small mammal run across the path. It looked dark in colour. It was no bigger than a cat or small dog, but this was no domestic animal. It was stocky but with no tail that I could discern. A stubbyish head. And I’ve no idea what it could be. Admittedly, I don’t wear my glasses when running, but I’m quite sure I’d recognise a picture.

I’m resting up at the moment – repairing the damage caused on my last run – but I do wonder what the subtly changing valley will look like next time.

(Any ideas on my mysterious mammal, very welcome. Comments here or at twitter.com/jonesy_boy as I’d love to know what it could have been!)