By this time next week I might just have the smug satisfaction of being able to call myself an ultrarunner – and no longer a mere marathoner. By this time next week – as a consequence – I imagine I’ll also be in a great deal of pain. An ultramarathon is classified as anything longer than the traditional 26.2 miles of a marathon. I’ll only be venturing a further 3.8 miles into the hallowed territory of ultra, but every physical step beyond a marathon will be a metaphorical step into the unknown.

My ultrarunning career will start in the inauspicious environs of Leatherhead, a Surrey town skittled by Martians in H.G. Wells’ dystopian novel, The War of the Worlds. The event is the Winter Tanners, organised by the Long Distance Walkers Association. There is a 20-mile course and a 30-mile course. Entrants can walk or run. I chose the least sensible option: I am running the 30-mile course, an out and back one among the Surrey hills. Entry was £5. It is the epitome of low-key: entrants start when they want to on Sunday morning; there are no prizes; there are three checkpoints serving tea and biscuits.

The Winter Tanners is a means to an end (I haven’t yet reached the stage of running a 30-miler for ‘fun’). The end, of course, is a Bob Graham round in June. The Winter Tanners is a giant leap – sorry, another metaphor – to that goal. Can my body cope with 30 miles? I have deliberately forced myself through a hard week of training in preparation – 58 miles, my highest mileage for 10 months, including a 27-mile weekend, before winding it down prior to Sunday. Not bad for the first week of a new year. I have paid for it, however. My body is creaking a little. My right Achilles hurts; I’ve plantar fasciitis in both feet that I can’t shake.

No matter, I’ll be on the start line on Sunday. Since the words ‘Bob’ and ‘Graham’ have entered my consciousness, I have adopted a new mantra: If I can’t do insert long run, track session, 10-mile run on a cold, wet, windy Thursday night after work etc, I definitely can’t do the Bob Graham. That mantra will be no more appropriate than during the Winter Tanners, the longest race of my life. If I can’t cover 30 miles of hilly terrain over the course of five hours, dealing with a raft of emotional and physical challenges, then there’s no way I can cover 60-odd miles, 42 Lakeland peaks in fewer than 24 hours in June.