I was arranging for our regular Sunday road ride. It was Shang who suggested we try something new instead, and turned on his charm to inveigle me to a trail run.
This would be up everyone's favourite semi-wilderness, Bukit Kiara, on the periphery of Taman Tun Dr Ismail, Kuala Lumpur.
On a regular weekend, it resembles a carnival, with runners, walkers, cyclists, families and apparently trail runners going back to nature, even if most people drive there in their air-conditioned cars and try to park as near as possible to where the actual walking starts.
Shang SMSed me: "Please don't drop me ya. Give chance ya." Since he regularly dropped me (leave me far behind) when we were out road cycling, I should've taken it as an indication of what was to come. I must've been sleep-deprived to miss the obvious.
Sunday was drizzly and grey - just as well that I wasn't going cycling.
I met the other half-dozen trail runners at the car park in Bukit Kiara and almost immediately knew I was in trouble.
Most of them wore hydration packs, or were at least carrying water bottles.
I was just carrying my keys.
I could also tell from their physiques that this crowd wasn't your regular bunch of stroll-up-the-hill types.
The organiser was Jessen, and another runner, Dave, a beguilingly cheerful Mat Salleh whose legs looked as if they'd been carved out of marble.
We were bantering, and Dave joked: "I'm ex-SAS (the British army's elite squad)." Pity I thought it was only a joke, otherwise I would've turned tail for the comfort of hearth and home then.
It started to rain then, scattering the families and walkers, sending them scurrying under shelter or back to their cars.
Not this bunch, though.
They didn't even flinch, and when everyone had turned up, we started up the mountain bike trail.
There is a spider's web of mountain biking trails, largely invisible to the walkers who stroll or jog up the hill along the tarred road.
The tarred road runs a 5-6km loop, but the bikers' trails are easily several times longer than that, and extend into Sri Hartamas.
We started out at a steady run, dashing up the hill along the narrow rutted trail.
The jungle was wet and dripping water, and the trail was like slush in places from the rain.
For all I knew, we could have been in a dense jungle somewhere in the wilds of the country instead of being mere metres away from cars, a main road and a major housing estate.
Up ahead between the trees and the steady drizzle, I caught glimpses of the other runners as they negotiated the path.
"This is fun!" I thought, as we ran up a rocky slope and jogged along the muddy path between old rubber trees.
Poor deceived fool, that's what I was.
Trail running is very different from road running, where you can keep to a steady pace on an even surface and see what's up ahead.
This was entirely different, with the pace varying depending on the terrain, and what was ahead was often impossible to tell, with sharp turns, sudden descents and quick ascents when you least expected it.
Tree roots, stumps, rocks, boulders, all make for quick shifts in the running pace to adapt to the terrain, so you really need to pay attention to what's under your feet.
It wasn't an activity for daydreaming. Very quickly, I had to fall back and let the others forge ahead.
The pace and the terrain were taking their toll, and I was relearning fast that muscles are very activity-specific.
I wasn't wearing a heart-rate monitor, but I was sure it wouldn't have been very happy with my performance.
Fortunately, there were stops to regroup, which gave me some face-saving grace when I ran up, wheezing and panting like an asthmatic patient on his last legs.
The drizzle had stopped - not that it mattered, since I was completely drenched from my own sweat, anyway.
Dave, looking almost sickeningly cool and cheerful, offered me a sip from his hydration pack.
He didn't even seem to be breathing hard.
"On the uphills, take small steps", he offered. "Use your legs like the gears on a bicycle. You can stretch out a bit on the flats and downhills."
At some stages, he'd been the sweeper and had obviously watched me proceed like a slow man in an extreme state of inebriation, tottering up the slopes or weaving along the straights.
We proceeded on, and we ran - or they ran, I walked - past a hidden lake.
I never knew there was such a network of trails on Bukit Kiara, although I often jog up the hill. Another short and brutal uphill stretch ahead.
"Hoo-hah! Hoo-hah! Hoo-hah!" First time I've ever heard monkeys howling on the hill, I thought to myself, and then realised it wasn't the monkeys; it was me breathing. Or some semblance of breathing anyway - it was more like desperate wheezing.
We burst out onto the tarred road from the gloomy jungle, and suddenly I knew where I was.
Mercifully, we walked for a short distance along the road, before re-entering the gloom of the understorey for another punishing bout of jogging along the trail.
Mr "Please-don't-drop-me-ya" Shang was the sweeper, having moderated his pace to a near-walk to keep pace with me. I snatched his water bottle and guzzled a good portion of it before continuing on.
At the cross-junction at the top of the hill, Jesson was plotting the route up to Twin Peaks, and Dave wanted to loop back down the route we had just come and run uphill again before tackling Twin Peaks. I was preoccupied with wondering if I had turned a greener shade of pale.
Discretion being the better part of valour, I decided to call it quits - my first piece of wisdom for the day - and bade them goodbye, taking the regular road down at a sane walking pace.
"So you are ex-SAS, aren't you?" I asked Dave, who just grinned.
He still wasn't breathing hard.
Perhaps Dave wasn't really ex-SAS, but he'd just come back from Kona, Hawaii, from the full Ironman triathlon, and that was bad enough.
As for me, I'd had my first taste of trail running, but I'll be back.
Between the fog closing in over my addled brain, and the sensation of burning in my lungs, it was fun. Really.