I can't go on, I'll go on, Paul Cullen intones as he completes his sixth Dublin City Marathon.
Every joint aches. I crave food but nothing will stay down. I've filled the bath with cold water because that's what the experts recommend for people in my condition.
Yes, it's marathon day again. I've just been for my sixth 26.2-mile jaunt around the streets of Dublin and it doesn't get any easier.
I was an idling student in 1982 when a record 11,000 or so runners participated, but yesterday's turnout was only a few hundred shy of that number.
A river of runners filled Nassau Street as the race started. The vanguard of this vast phenomenon hit Merrion Square, while I remained becalmed at the junction with Grafton Street.
Indeed, I was still at this junction as the front runners passed Holles Street Maternity Hospital and headed down Mount Street.
The race was on for almost 10 minutes before I managed to cross the start line and my timing chip was activated. I might be on Nassau Street still had I not politely squeezed past the man in the bridal dress who was standing in front of me, talking to his friend in the Superman outfit. Then there were the people on the mobile phones, the arm-linked and somewhat scary lines of American walkers and the hundreds of runners still queuing for the Portaloos as the race got under way.
In short, the start was a mess. At a late hour, the organisers abandoned plans to segregate runners by their expected times, so walkers and fancy-dress artists ended up in front of people who actually wanted to run the race.
And so I spent the first few miles following a mazey path across roads and pavements in search of an opening in the crowd. The problem got worse as we ran up O'Connell Street, where yet more building work reduced the road to a single lane.
In no time we were up on the North Circular Road, looking its autumnal best in bright sunshine. The Phoenix Park, where the deer joined in the spectating, was even lovelier.
These were the good times, but they weren't to last. Past Inchicore and the cheers of family and friends, I turned on to the South Circular Road - and into the wind. For most of the remaining 16 miles, the wind was to taunt us, gusting unexpectedly from all angles and never seeming to be in our favour.
The hill up to Crumlin children's hospital and the Halfway House pub was particularly tough in a constant headwind. Things had been going well up to then - I was a minute up on my schedule for a 3:15 finish - but the omens were not good.
Training for the marathon is quite simple: you run a lot. An awful lot. I had run quite a lot and I was about to pay for it. My stride shortened, my head sank and I started looking around maniacally for people offering sweets or bananas - any kind of succour. Having overtaken people for miles, it was now my turn to be passed out.
But you learn things having run a few marathons. You don't arrive too early, so there's no needless waiting around in the cold at the start.
You don't drink too much because what goes in must come out - a lesson not learned by hundreds of runners yesterday who were forced to make a pitstop within minutes of setting off. Finally, you don't stop, if only because starting again is awful.
So you keep on keeping on. It isn't easy when you start feeling dizzy and list to one side, but by now you know that the finish is only a few miles away.
The cruel wind caught us again on the Stillorgan Road and outside the RDS, just when a little help might have been appreciated. But at least the crowds were plentiful and boisterous in their support. Suddenly, we're in town again and the finishing line is approaching.
Time for a little sprint, just from the last corner on Nassau Street back on to Merrion Square. The din is enormous but my head is spinning.
I half-collapse over the line and stop my watch - 3:27, as fast as I have ever run a marathon in Dublin.
And then I make a promise. Never again! This time I mean it.