After a couple of weeks of solid training runs, my thoughts have been turning to what this is really about.

Ever since my failure to finish in 2013, I knew that my next attempt could only be for one charity – St John Ambulance.

Their team of volunteers were there in my hour (or so) in need and running the marathon this year is a way of me repaying a debt to them.

Tonight I received my charity pack through the post, offering all sorts of training and fundraising advice. But what stands out for me are the statistics.

Only five percent of the population have been trained in first aid, and 41 per cent have said it would take something as severe as the death of a loved one for them to learn life-saving skills.

I find those two points quite staggering, but equally very understandable. I have been on a first aid course myself – but that only came about as a result of collapsing in London.

Yet a £25 donation pays for 200 first aid guides who can pass on essential advice, and £120 would mean 32 children could be taught first aid by a qualified trainer.

On Sunday I will be attending the Watford Half Marathon to see first-hand how those connected with St John Ambulance play their part in one of Hertfordshire’s biggest running events.

I don’t need a reminder of what essential role they play on such occasions but I’m intrigued about what goes on behind the scenes to make the life-saving support they offer possible. And if I can pass on this message to others, all the better.

• To sponsor me and help support St John Ambulance click here.