Terror paralyses you. You can’t move. You can’t think straight. Your body goes into a state of hysterical paralysis. It’s like someone has turned up the music to an impossible volume and you’ll never be able to find the control. It drives you crazy.

I’ve never experienced it before. I’ve been afraid before, or anxious, but never terrified. But then I’ve never been lost in the jungle before.  As it happened, the phrase kept on repeating in my head over and over again, like an emergency alarm. ‘Lost in the jungle’ seemed a monumental sentence. Unlike the problems you’d usually face, this could realistically end with death. Admittedly, I’m not sure it was technically a jungle. I have no idea what the technical definition of jungle is. But for me, it is a place that is covered in trees and fucking terrifying to get lost in.

I’d looked in every direction and I couldn’t find the trail. I had no plan and no idea where I was. No one knew I was there. I was well and truly screwed.

The expedition was ill-prepared from the start. I’d taken to walking up mountains recently. Nothing really masculine – no ropes or climbing or the like – just arduous strolls really. They beat off a hangover like nothing else in the world and there’s something really satisfying about spending the evening drinking, then climbing a mountain and starting to drink again with people who’ve been at their job all day. You get all the accomplishment and none of the work.

So I woke up hungover on Saturday morning and thought I’d try to reach the summit at El Cani, a 1,500 acre private nature reserve about 20km east of Pucon, where I was staying in south Chile. You could tell from the few other people I saw in the park that the trek, which goes up 1,500 metres on treacherous, winding pathways, was demanding. They all had large backpacks, were loaded up with water, and carried those weird skiing poles you see hikers with sometimes. I had shoes from Zara with literally no grip at all, a Ted Baker manbag, 750ml of water and an empanada. Basically, I was an idiot. I’d avoided all the tours and tourist excursions available Puco and headed on my own on a local bus to the reserve.

The woman at the entrance office seemed a bit perturbed by how I as dressed. Are you sure you don’t have any questions? she asked as I set off. I told her it was fine.

The map and the trail were clear enough, but it was hard going – much harder than I thought. At 600 metres elevation I could feel my brain beating in my head and I was covered in sweat. My clothes were sticking to me. I was constantly fighting the temptation to just down the water. My shoes were slipping and sliding all over the place.

There was a lodge marked in the trail, about halfway up. Leading off from the lodge seemed to be two light trails. It didn’t occur to me that I could open the gate, pass through the lodge and follow the trail on the other side. Instead, I spent my time irritably trying to figure out which of the two light trails to take.

This is a common error in the way I think. I can’t even count the times I’ve spent an hour lost in a video game, exploring unpromising corridors, then returned to where I originally was and seen a big open door there. It’s also why I’m shit at chess. I’ll spend ten minutes working out my strategy five moves ahead only to watch my opponent move their bishops two spaces and take my queen. I have a tendency to get lost in the reasoning without first having established the basic parameters of the question.

I tried the trail which looked more inviting, but it was going downhill too much for my liking, so after a few minutes I retraced it back to the lodge and tried the other one. It was here that my judgement became seriously impaired. After a while there plainly was no trail at all but I started imposing one on the landscape. Surely this fallen tree trunk meant I should stick to the left, I thought. Surely this expanse of grass was inviting enough to stand in for the road. Each time I made a decision like that I kept on trying to photocopy the image of the route I was taking into my brain so I would remember which way I’d come if I had to double back.

If you had told me that what I was looking at was a trail at the start of the trek, I’d have laughed at you. It’s true that the route had started as a wide road and gotten progressively smaller, but there are no excuses: my reasoning was extremely poor. It had been degraded, partly through exhaustion and lack of water, partly through bloody-mindedness.

I started trudging through a dark, soggy canopy, where the muddy ground, mixed with old fallen trees, crackled beneath my feet and vividly coloured, almost cartoonish mushrooms burst out from the bark. Large and silent black insects, like flying ink dots, kept flying around my face. And still I pressed on.

After about five minutes I got to a large fallen tree and started to clamber over it. At the top something stopped me. Surely this was too much, I thought. Lots of people wouldn’t be able to climb this thing. I hesitated and then remembered where I was and decided to turn back. But even then there was a voice in my head poking at me for being cowardly.

Once I was off the tree, some degree of sense returned and I quickly became nervous about my predicament. None of the photocopies I’d tried to take with my mind’s eye had worked. Any two directions back looked the same as each other. I could feel the panic rising in the back of my throat. Earlier I’d told myself that if I got lost I could just walk downhill, but that does no good at all. The area is crowded with ravines and valleys and mazes of trees.

And then I did something very stupid: I kept making decisions. I switched into militarised public school mode.

I hated public school and I don’t believe in it. It was an unpleasant, unkind experience. But there’s one good thing about it: the constant leadership message they hammer into you does take over in times of emergency. When things get serious, I feel a burning need to take charge, to make a decision and implement it, never to fall into uncertainty and fear. It’s served me pretty well through the years. I’ve always been reassured by that part of myself taking over in times of crisis.

I started walking and simultaneously scanning the environment and concluding very quickly which of the sights would have looked more like a path to me a few minutes earlier. But I was fooling myself. I wasn’t really making decisions. I was barely evaluating the environment at all. It had become far more reassuring to me to be doing something, to be walking in a given direction, than it was to stop and accept the gravity of what was happening.

I have a tendency when there is a problem – whether it is mine or someone else’s, whether it’s romantic or social or professional or whatever – to want to break it down into manageable goals and work out what actions it would take to secure those goals. I only really get depressed about something when there’s wallowing. I need to act, to be doing something about it, and no matter how bad things are I start feeling better about them as soon as I do. Now that tendency was betraying me. I was afraid of standing still and accepting that I was lost, so I kept making decisions, I kept moving, even though it was plainly making the situation worse.

It wasn’t a practical strategy. It was an emotional one. Arguably during this period I had become functionally insane. I was committing counter-productive actions because of how they made me feel rather then their consequence in the real world. After five minutes of this, I finally realised I had no idea where I was. I was lost in the jungle.

That’s when the terror struck. It was exactly like they describe it in books: icy fingers closing around my heart. It expressed itself in the form of claustrophobia. Being lost didn’t feel like a state. It felt like a place. And wherever I went – whether I walked five steps left or right – I was in the same place, the place called lost. Lost was like a thick wooden coffin closing in on me, like something I could feel my breath against.

The moments of terror, when I became inactive with panic, lasted a minute or so at a time. Then I’d get a wave of reason again. I started to think about rationing what I had. I’d about 400ml of water left and half an empanada, as well as some mints, which I was hoping might give me a sugar boost if necessary. I couldn’t sleep on the ground – there were reptiles and massive spiders everywhere and I’d read on the internet there were pumas too. I’d have to climb a tree and sleep there.

I wondered when people would realise I was missing. The woman at the entrance wouldn’t. People camp up here all the time. And anyway, I hadn’t left a phone number with her. I was meeting my friend Zita in Santiago the next day, but she was a new friend who communicated with me, like everyone here, on WhatsApp. She was unlikely to call for a rescue because I didn’t turn up, and anyway she didn’t know where I was. I didn’t tell my family I was staying in Pucon. My only hope was that I’d mentioned the park I was in on Twitter earlier. If hadn’t contacted them in a couple of days, when my flight was due to take me to them for Christmas, my family would inevitably have searched Twitter for what I had been doing, given that I’m always on there babbling away. But two days obviously seemed a very long time.

There was no reception. I checked my phone anyway and the no-reception icon made me feel terribly alone. It’s ridiculous of course. Google maps was hardly going to show a path which anyway did not exist. But I’m so used to this object guiding me that its sudden uselessness sent a shiver through my heart.

All told, I was lost for about half an hour. Half an hour of pant-wetting, bona-fide fucking terror. Eventually I saw a line of mud amid the grass and followed it. I think it was the downhill trail I’d half-heartedly followed for a bit earlier. It led me back to that camp site.

I sat down and let the panic subsume, which took a while. Then I had a choice to make. Finish the climb or head back down. I decided to finish it. I didn’t want the last proper day of travelling to be a memory of failure. So I started climbing again. At the time, it felt like the bravest thing I’d ever done. The route got tougher. My boots were slipping and sliding all over the place, next to canyons and crevices.

The Mapuche Pewenche people ask the Pewenche trees permission to enter as they near the summit, at about 1,400 metres. I did the same. I wasn’t being flippant or superstitious. Embarrassingly enough, I actually meant it. My nerves were shredded and I figured that, atheist or not, I could use all the help I could get.

The view at the top – with five snow topped volcanoes in a 360 degree view – was spectacular but it only brought on another wave of anxiety. Now that I could see for miles in the distance, I realised how far away from anything I was. The trail, no matter how vertiginous or slippery, was mentally easier. It meant ‘go forward’ and that’s about as much as I could handle. Seeing it all from the peak brought back that feeling of claustrophobia.

But just down from it there was a wooden symbol signifying that you had reached the peak. This meant much more to me. It was a sign that I’d swallowed down the fear I’d felt, kept climbing and accomplished what I’d set out to do. I didn’t take a photo of the five volcanoes, but I took a selfie of me by the wooden symbol. By this point, it was more about me than it was about the view.

The way down was just an exercise in pain really. My feet, ankles, knees, calfs and lower back were killing me. At any moment, my shoes would slide downwards and I’d have to frantically try to rebalance. I was by this point completely out of water, drenched in sweat and emotionally and physically exhausted. But I made it, with half an hour to spare for the last bus into town.

Was I really in that much danger? Probably not. No matter how bad my reasoning in those crucial ten minutes, it was still only ten minutes. There were 36 people in the park that day, all following the same trail. If I’d stood where I was and shouted for help for long enough, someone would have heard, as unseemly and embarrassing as it would have been.

And the crevices and dramatic slopes which blocked my way, crevices which put the fear in me when I was lost, would actually have been helpful in limiting my options, if I’d stopped long enough and thought in a structured way about how to get back. Eventually I would have started to do that.

So why the fear? Well for a start you take a Londoner and make him lost in the jungle and he’ll likely shit himself, because it’s so far outside his spectrum of experience. But it was more than that. Being lost represented the ultimate loss of control. I couldn’t make my problem submit to my way of coming to a solution. The method I use to impose order upon the situation had actually made it more chaotic. And the endless maze of trees and slopes resembled the inner panic in my head in a way which exacerbated both of them.

It felt like a mental earthquake: the terror of something solid and reliable shifting under your feet.

When I got back to town I had a pint of cold beer. Then I found the best restaurant around and bought a steak. I ordered the most expensive Chilean red on the menu and followed it up with a pisco sour. I thought about the jungle, now cloaked in darkness. I’m not sure I can ever remember anything tasting so good.