When I trekked up Mount Kinabalu in my 20s, I was untrained and uninformed, and took eight neverending hours on the first day, instead of the average six hours.
Descending the second day was far easier so I ran down joyfully, naively compensating for the gruelling ascent. My poor, tender joints took the impact and my knees burned for days.
Years older and warier now, I am trained and garbed to confront a 4,095m mountain that still rises tantalisingly in my memory as a purplish-grey behemoth in the pre-dawn light of Sabah.
My focus this time is the Via Ferrata atop Kinabalu. This route, which lets climbers traverse the sheer rockface on a network of ladder-like rungs, long cables and narrow foot-bridges, was not yet built on my first trip.
The two-day adventure begins at the Timpohon Gate of Kinabalu Park, a Unesco-listed World Heritage Site. I take the Timpohon Trail, a 6km route that starts at 1,800m. It is shorter and more relaxed than the alternative Mesilau Trail.
I have signed up solo with a Singapore agency, Adventure Quests (www.adventure-quests.com), which teams me with six friends in their 20s and 30s.
With us are mountain guides from the Dusun tribe - Mr Cornelius Sanan, 33, and Mr Jabadi Iainsin, 32. They double as porters, shouldering our baggage which weigh a combined 33kg.
At 9.15am, we start. Gentle trails are interspersed with uneven steps that require stamina and time to catch our breath. We make good progress and are halfway through our 6km trek in a little over two hours. Not long after, we open our packed lunches at one of seven huts that dot the trail, and in retrospect we stop too long.
From then on, it is equal parts struggle and elation. I love an open stretch of rock, where mist rolls in, and it feels like a pristine moment in time. Soon, the soil turns ochre and I look for insect-gobbling pitcher plants.
Around the 4km mark, at Layang-Layang Hut, I part company with my group, as they are now uncertain about attempting the Via Ferrata.
I have to arrive at the accommodation complex by 4pm for a mandatory Via Ferrata briefing. Mr Sanan joins me, pacing me for the last two rough kilometres.
While it is rejuvenating to pass by a serene forest of mossy trees and round, dark-grey, granite boulders, I do face several steep gradients. The terrain keeps changing, as if the same mountain has different guises.
The weather, too, changes from sparkling, uplifting sunshine to playful puffs of mist to threats of rain.
In the last 500m, Mr Sanan encourages me a couple of times: "You are very close now."
And finally, 61/2 hours after we begin, I arrive in time for the 4pm Via Ferrata briefing at the Pendant Hut. Walk-in guests can also attempt the Via Ferrata if they attend this briefing.
It is an early night after dinner and mountain viewing. Trekkers fall asleep between 7 and 8pm in the mixed dormitories, for we must be awake at 1.30am to get ready for our summit climb.
I sleep intermittently in the silken sleeping bag supplied by Mountain Torq, which manages Pendant Hut and the Via Ferrata trails.
By 2.30am, after a light breakfast, we are off. As we ascend, I watch the lines of trekkers in front and behind, their headlamps twinkling like terrestial stars. True stars stud the night sky, and sleeping towns lie at our feet.
It is a clear night and these scenes differ greatly from what I glimpsed on my youthful trek, when mist obscured every rockface. I kept thinking I was on the verge of reaching the top, but then the mist would lift partially to reveal steep, mysterious slopes beyond.
"You never climb the same mountain twice, not even in memory. Memory rebuilds the mountain, changes the weather, retells the jokes, remakes all the moves," writes author and ski instructor Lito Tejada-Flores.
I do recall the mystique and beauty of my first summit attempt, rather than the pain.
This time, Mr Sanan is an immense help. He gives me his hand occasionally so I can move quicker up the rocks. "Control your breathing,'' he counsels.
I step on the summit just before 6am. The sky is tinted pink and purple, but it is too cloudy for full sunrise splendour.
I walk down to Sayat-Sayat Hut where my Walk The Torq climb will begin. The Via Ferrata is my principal goal on this trip and is a new adventure that liberates me from high anxiety.
When it is time to leave Kinabalu, the descent saps me. Going down, I wear knee guards, yet I descend slowly and painfully. The calves and ankles start to protest, and I have to tend to blisters.
"You are challenging only yourself and not others on a mountain," I overhear a philosophical trekker at one hut.
It is true that I am pacing myself against my younger self. My constitution was more robust then, even if I am now fitter, more determined and richly informed. I keep having flashbacks of trekking with a dear Spanish friend I have not encountered since.
It takes me six hours to descend. I calculate that I have been on the move for 12 hours since 2.30am, not counting breaks for repacking and brunch.
Will there be a third time on Kinabalu? Possibly not.
But then a trekker in our group mentions that in 2000, he had climbed both Kinabalu and Kilimanjaro, the roof of Africa. It made sense to conquer two mountains in one year, he reasons, as he was at peak performance.
And so now I dream of Kilimanjaro.