The male mid-life crisis takes many forms, most of them fairly ridiculous. As a male in mid-life, I have so far resisted the more extreme versions but I have to admit I've been tempted.
The more clichéd scenarios involve the purchase of low-slung sports cars (often in fire-engine red) which the middle-aged owner has some difficulty getting into and out of.
Then there's the full hair-transplant, botox, fancy architect specs, dressing younger, using supposedly cool street slang, Nicky Haslam version.
Or there's the affair with an Eastern European pole dancer which apparently looks and feels like true love, except it isn't.
The cheating, crisis-riven male then announces to his wife that "the heart wants what it wants" and goes on to lay waste to his marriage, his family and his golf handicap.
There are more harmless versions involving sudden resignations from well-paid, steady jobs to keep pigs in west Cork or sail around the world in a Pot Noodles tub.
But there is yet another form, all the more insidious because it comes bearing respectable exercise and fitness credentials.
This manifestation of the male mid-life crisis looks normal, even healthy, yet it poses the same dangers to marital harmony as all the others. It is the triathlon.
Something comes over many men in their 40s. Perhaps it is a nostalgia for their sporting past, or maybe it's a last chance to create a sporting past.
Typically they begin with mini-triathlons (or sprint triathlons), which involve a 750m swim, a 20k cycle and a 5k run. This, apparently, is like the first taste of crystal meth: tough, but exhilarating enough to get you hooked.
Just as with any addiction, it soon tires of the entry-level high, and begins to crave something more. Enter the Olympic triathlon, a 1.5k swim, 40k cycle and 10k run.
An otherwise healthy male in full-blown mid-life crisis may then go on to the Ironman Triathlon (2.4-mile swim, 110k cycle, followed by a marathon).
There are other symptoms to the triathlon crisis: an almost fetishistic attachment to lycra, rubber and bicycle gear cogs.
The wives of these men are often put under extreme stress during the crisis years. They have to pack up the family and drive to some god-forsaken river estuary every other weekend to "cheer on your father".
They have to listen to endless dinner-table conversations about his T1 and T2 times (the transitions between the stages, requiring changes of apparel) and the chaffing of his cycling shorts.
"I think it's another excuse for them to go out and buy lots of kit. Bikes, wetsuits, running gear, all that," says one long-suffering wife.
"And I think it's an excuse for them to get changed next to fit young women," adds her friend.
I will admit that I was tempted to try a sprint triathlon (even though I found the word 'sprint' a little off-putting). It was the absence of a smoking area that put me off.
Then an email arrived from a friend in the US. I'd heard he'd gone all lycra over there, and now I saw it was true.
Further enquiries revealed that he could not see a body of water without wanting to do laps of it, or a stretch of beach without wanting to run up and down it. Life was one long triathlon training session. Probably times himself changing into his pyjamas, I thought.
He was suggesting that a triathlon between the group of families who meet up in Connemara most summers. The US-based ones against the Irish ones. Or, to put it another way, the fit ones against the unfit ones.
The proposed course was scenic if nothing else: two lengths of the enormous lake at Ballinaboy Bridge, a cycle over the bog road to Roundstone and a run to Keogh's pub in Ballyconneely.
There was some back-and-forth by email, and I could see the blokes -- all of us in our late 40s -- were attracted to the idea.
After all, it was sporty, manly and could possibly exorcise any competitive issues remaining since we were all at UCD together in the 1980s.
I thought I might have a slight advantage over the others: I knew the course well. I had done that very same swim, cycle and run myself. Not in the same summer, of course.
Negotiations are ongoing. I can feel the pull of the mid-life crisis. "Go on, Dave, you can do it," a voice says to me.
"Wait for them in Keoghs," says another voice. My wife's.