Some of those reasons are personal, although I have written about them and even spoken about them in the three radio interviews I've done. I've also been inspired by some people - including cricketer Marcus Trescothick, whose autobiography was, at times, incredibly moving - and affected by others, the late Gary Speed being the most notable.
Obviously, a lot can happen during a year-long challenge. For example, whilst I was pretty certain that I was going to turn fifty (June 3rd if you want to buy me a present), I suppose I was less prepared to find out my job will be disestablished in a few months time. But my own problems and worries pale into insignificance when someone you know passes away both unexpectedly and in awful circumstances.
The person in question was Sharon Evans, someone with whom Elaine had worked for well over a decade. I knew Sharon reasonably well, but plenty of people on the team were extremely close to her. In the scheme of things she wasn't particularly old, and whenever I had been in her company, Sharon was almost always chatty and outgoing; great with the blood donors at work, and blessed with a seemingly never-ending wardrobe for nights out.
Sharon was simply not the sort of person you would have expected to suffer from depression.
But she did.
There may have been a reason, a trigger, I don't know - and frankly it's none of my business - but there could just as easily have been no explanation at all. Depression is such a cruel form of mental illness, essentially unseen, sometimes badly misunderstood, but potentially so destructive, and the absolute tragedy is that Sharon's personal anguish ended with her taking her own life.
I cannot imagine Sharon's pain.
I cannot imagine her family and closest friends' grief.
But I can take this opportunity to thank Sharon's friends and colleagues from work, who have asked that part of their collection be donated to Mind in memory of a very courageous woman.
That I shall do with sadness, with respect, and with an even greater determination to complete my challenge.
Rest in peace Sharon x.