I got up early and had my porridge delivered by room service at 6.30 am, not because I am posh, but breakfast downstairs was too late to allow me to digest before running.
At 8am I jogged round to warm up, joining the thousands of participants.
As well as the marathon there was a fun run, an eight-mile walk and wheelchair race - 20,000 people in all. Belfast was rammed.
Although I didn't know anyone, my friends at the Law Society of Northern Ireland had told their two relay teams to look out for a middle-aged guy in a black Batman top and a Chicago baseball cap.
They might have added "and a worried expression" to that description.
I was spotted and they offered to run with me, but I graciously declined, not wanting to hold them back.
The route took in some interesting areas.
The Falls Road was on the way - complete with the new Gerry Adams mural, and about two minutes further on we crossed over the Shankill (I never knew they were so close to each other).
Spectators lined the route, several deep in the city centre sections, and as predicted, the Batman top was a draw to the eye.
I lost count of the shouts of encouragement - and a few of humour and even ridicule - during the race.
I hit the wall at 17.5 miles, after the four miles or so of the Antrim Road - all uphill, followed by a twisting route down to the river cyclepath.
I took nearly six hours. But it was never about a time, it was only about preparing, training, improving my diet, and completing the project.
I am coming up to my 55th birthday, after all.
I can now tell you what I kept to myself and the First Lady - that I damn near missed out on running the race at all.
Regular readers will recall I had two incidents during training - one was food poisoning, which just put me out of the running game for a couple of weeks, and the other was a busted left knee/leg/foot.
The latter problem was bad. I never really recovered, and whenever I ran I had substantial pain in the metatarsal area under my right foot.
My final run - not that I knew it would be the last - before the race was on April 28. I did a neat little three miles on the treadmill.
The following morning I was hirpling like a zombie, dragging one leg behind me.
Ok, I understand that in an ideal world I would have let myself heal. But the stakes were too high.
I've written before that the publicity surrounding my efforts is something I am extremely conscious of, and the responsibility created by raising thousands of pounds for St Margaret's Hospice has been both carrot and stick.
There was simply no way I would not be at the starting line on Monday.
My weekly column has been about personal responsibility, achievement and objectivity.
The final preparations for this race have been a perfect case in point.
Ultimately you can get support, friendship, advice, encouragement, but it is up to me. No matter how deep, I had to dig out the attitude, performance and guts to run 26 miles.
Before I finish, I want to thank a number of people.
Evening Times readers have been supportive and interested in my progress.
Friends and colleagues have encouraged me, and/or made financial contributions to my charity effort.
Between www.justgiving.com/AustinLafferty and some old-fashioned cash and cheques, I have raised more than £3000.
I was stunned when an elderly friend told me he would offer £10,000 between a current payment and a will bequest.
Apart from there being no way I would not have been at the start or finish lines, I am actually humbled by the faith shown in me and the generosity of many people with their own concerns and charitable interests.
I must thank our friends Imelda and Jim McMillan, who looked after us in Belfast and I must pay tribute to my wife Yvonne.
Her positive thinking, relentless cooking of carbs, and occasional corrective remark, all helped me a great deal.
So I did it, and I am proud of myself. But I think I may give the running a rest for a while.
At least until I stop limping. Anyone need an extra for a Zombie movie?
Actually, this column should stop there. The last few months of writing for you have been fun, and have been about health fitness, diet, but all predicated on the race, which has now been run.
But it all seems to have struck a chord. The Evening Times has asked me to stay on, writing on these subjects regularly in a wider context.
I will be delighted to do so, as I believe any encouragement I can give in no matter how small a way is worthwhile if readers can take the example of a middle-aged deskbound man who tends to over-eat, and do better.