Basically, the fundamental of an Ironman training plan is to make sure I'm covering significant distance in running or cycling pretty much every work day, and then wedge in some swims where possible, before really hitting it hard at the weekend - although thanks to my shoulder injury (getting better, aiming to be back in the water next week), I haven't swum for nearly a month, and that's getting to the point of quite serious frustration.
'Significant distance' means, basically, running 20-22km per day (roughly 12-14 miles), or cycling 60-90km (roughly 35-60 miles). Fitting that in around work hours really isn't that easy, even on logistical terms - it's basically 2-3 hours of training every day. But it's when you then expect yourself to be on reasonably constructive form for the time when you are at work, that you end up in trouble!
As for 'hitting it hard', this weekend that involved a 150km, 7 hour ride in the Dorset hills. Which was really enjoyable, up to a point. That point came about 130km in, at the bottom of the hill in Little Bredy, just before churning my way up to the Hardy monument. Then it suddenly wasn't fun any more. Cyclists call the feeling I had at that moment 'bonking', and it's not nearly as much fun as what most other people mean by that word. Your legs suddenly stop following orders, and go into active denial of the purpose that you're trying to drive them towards. Your lungs are burning, in my case to the extent that I was genuinely struggling for breath. And to top it all off, because you're going up a steep hill, you're basically not even moving. At that moment, a fat man on a slightly hurried waddle to the bus stop could have outpaced me.
Oddly, though, there is something - at least for me - pleasurable in this feeling as well. It's a moment when you really come up against your limits as a physical being, finding the point where there genuinely isn't any more you can do. This is an amazing place to go, and I think a really powerful moment to take into the rest of life.
An old rowing coach of mine, Mark Hall, once told us in a pre-race briefing that we could do ourselves no damage by testing ourselves to what we thought was the limit. When our brains told us to stop, he said, we would be at 60% capacity. When our brains screamed to stop, we would be at 80%. And when we were at 90%, we would pass out anyway. Which would be fine in the long run.
I remember these words from 12 years ago every time I hit the wall on my bike, or on a run... and actually sometimes when I've got too much to do in another part of my life. And I push a bit harder.