The chosen route, known as the GR 20, meandered for 180 kilometres over virtually the entire north to south length of the island. It included 12,000 metres of ascending and is considered the "toughest trail in Europe". 

I think I was vaguely aware of this when I agreed to do it. But, despite having no hiking experience nor climbed anything more strenuous than the hill up to the Palace Hotel in Lausanne over recent years, I blithely figured that it couldn’t be too hard.

My confidence was boosted by a reassuring neighbour who, having done part of the course a few years before, gave the impression that so long as you started early to avoid the heat, it wouldn't be too hard. "You will have plenty of time for beers and relaxing after if you do it that way," he added.

This sounded good. I therefore armed myself with kit no more advanced than a head torch, walking poles and some supposedly long-lasting "odour-resistant" boxer shorts and, trying my best to ignore the many pearls of wisdom from my dad - "a line of string is absolutely vital", being the most memorable - we set on our way.

The route was split into 16 Tour de France-style stages, with "refuges" and campsites at the end of each one. Our original plan was to take 14 days, though we rashly amended this to 13 so we could enjoy a day on the beach at the end. This meant three gruelling "double days" of even more walking.

A first sign that the trip was not going to be as straightforward as first thought came when we arrived at our airport hotel before an early morning flight to find that our confident group leader had somehow booked one of the rooms for the previous night. 

With no others available, three of us got out our sleeping bags and spent our pre-trip night of luxury lying on the floor of the other room, desperately hoping nobody checked why there were so many people sleeping there.

A second such indication for concern came when we shared a taxi from the airport to the starting point with a lady who seemed to have spent most of her life on such trips. Having heard story after story about the perils of different parts and being dazzled by the complex nature of the equipment she was either bringing or not bringing - she lost me when expressing her reliance on something called "freeze dried food" - I was already feeling out of my depth.

Her main piece of advice was to wait until the next morning to start in order to avoid the midday sun. We decided to ignore this and set off up the opening climb. She had also warned us to keep our bags as light as possible, so we reduced our water supplies before beginning. "Basic semi-survival," said our group leader, who spends most of his free time watching the likes of Bear Grylls on television.

Naturally, we had made two huge errors here and were soon gasping for liquid in the sweltering afternoon heat. Just when we got it into our heads that we had nearly finished, the already impossibly-steep trail ceased to bear any resemblance to a path and instead climbed straight up a vertical tower of rock. 

We completed it, just, despite dehydration and exhaustion, and pitched our tents with difficulty on a slope so steep that, when I clambered out the next morning, I tripped over a guy rope and slid down the hill straight into a friend’s tent, delivering an unorthodox but brutally efficient wake-up call.

So set into motion a daily grind of pain and torture.

The early stages were the toughest, with never-ending climbs up mountains stretching into the clouds followed by equally terrifying descents alongside huge drops. I tried not to think about the consequences of one false step while wondering how the trail had evaded the notice of health and safety inspectors. 

The fourth stage had been re-routed in 2016 after a storm-triggered landslide the previous year had caused the death of seven people. We avoided this, but our relief was short lived as the diversion instead took us 2,600 metres up Monte Cinto, the highest mountain in Corsica.

When we finished each day, we relaxed in the sort of campsites which made me determined to never criticise media facilities again. 

The "toilet" was often no more than a hole in the ground and, on one occasion, to have a shower was a three-man job in which one person had to turn on a pipe before another had to carefully thread it over the wall of the cubicle to be received by the person inside. 

If you were unlucky, all your clothes next to you were drenched and you were left dry but shivering. (My dad, for the record, had been absolutely right, as a line of string proved invaluable for drying your clothes afterwards).

If you were really unlucky, the hose hit its target and you were attacked by a sudden torrent of ice-cold water.

This is not to say the trip was not fun. 

The scenery was stunning and there were all sorts of beautiful rock pools to stop and swim in on the way. Food was usually basic but occasionally fantastic. On one night we stayed in an out-of-season ski resort complete with a restaurant at which we gleefully ordered two main courses each. "Semi-survival, we have to eat as much as possible," quipped my friend again, without a hint of irony, as he digested his steak and beer.

There was a great sense of camaraderie among the many fellow hikers we met. They consisted of a huge mix of ages, abilities and nationalities. It ranged from a group of Polish army-types who seemed to be completing the whole route in about seven days carrying no tents or supplies other than large quantities of alcohol - supposedly for the evening but quite possibly for the walk as well - to a group of British students who were equally as unprepared as us.

It gradually dawned on me that I seemed to be suffering more mishaps than most. By day six, I had developed huge blisters on the soles of my feet which were making every step agony. After being reduced to an even slower snail’s pace than normal on one descent, I was encouraged to try and pop the blisters - with a friend’s help - on the side of a mountain in order to reduce the pain. 

Stomach problems developed at another point, from a dodgy water-source no doubt. But the biggest hardship came late on when, literally a few hours after somebody had helpfully told us that "more people die on the GR20 from lightning strikes than from anything else", a huge thunderstorm broke out as we slept at the top of another climb.

My tent had been the envy of the group until this point as it was larger and easier to put up than anybody else’s. But it was essentially a beach tent and, as the wind pulled and the rain poured, water began to enter from all angles at an alarming rate. Realising that my presence in the tent was probably the only thing preventing it from being blown off the mountain, I resolved to lie in a drenched sleeping bag counting down the minutes and shivering from 11:30pm until the morning.

Two of our group ultimately just did the first week but three of us, somehow, managed to finish. This was an anti-climax. We marched through more rain into the concluding village of Conca - "we came, we saw, we conca-ured", bellowed our group leader - to find the locals decidedly underwhelmed by our feat of physical brilliance.

As we savoured completing the trip while sipping cocktails in sunnier weather on the beach the following day, I had a few thoughts. One is that I have new respect for Tour de France riders who began their even longer stage-littered quest on Saturday (July 1) in Düsseldorf. To go day after day is so difficult and, to a small extent, I can understand why some are tempted towards illegal substances to aid their recovery. Then again, I would have felt a far stronger sense of guilt at betraying the ethos of the walk by cheating. 

A second lesson was on the importance of good equipment, one of many areas where I failed miserably. A third was that, no matter how poor your preparation and physical condition is, like with most things in life, it is more in the head where the real battle is won and lost. If you steadfastly decide you are going to complete something, then you probably can. 

Next year, though, I’ll probably opt for two weeks on the beach.