Mud. Up to my knees. And rain. Heavy rain. A long day trudging with a heavy rucksack, head down, shoulders hunched against the cold wind. The only good thing about today was that it would eventually end.

I was trekking across the lunar highlands of Iceland towards the Hofsjökull glacier. My friend Chris and I were alone in the wilderness, carrying a month’s supplies on our backs. We had endured wading icy rivers and crossing lava fields that bruised our feet, but this evening’s mud was the worst. This was the last straw at the very end of a horrible day. 

All I wanted to do was pitch the tent, escape from the weather and go to sleep. Instead, I was stuck fast and struggling in a soup of mud, stones and boulders. I was filthy and exhausted. 

‘This,’ I growled to Chris, ‘is definitely Type 2 fun.’

Writing this description today in my shed, I looked back at some photos from Iceland to remind me of the details. There’s a picture of me, bent double in exhaustion beneath a massive pack. Retrospectively, the memory strikes me as hilarious. It was an experience I am definitely glad to have gone through, despite how furious and miserable I felt at the time. 

In a similar vein, I found rowing the Atlantic to be mostly a cocktail of nausea, misery, fear and boredom. And yet when the four of us gathered seven years later for a reunion in a small curry house in Cornwall, our recollections were very different. We spent the entire evening convulsed in hysterical laughter, to the bemusement of the other diners. It was one of the happiest gatherings I have ever been to. A gruelling experience had been polished by time into something precious and gleaming. 

The pursuit of retrospective pleasures is a recurring theme in my life: the warm glow of achievement after icy swims and hot deserts. 

Sensible people choose to spend their time doing things that are conventionally fun in the here and now. Eating cheese, Morris dancing, listening to the snooker on the radio – the usual stuff. These activities can be labelled as Type 1 Fun. If you smile while you’re doing it, you’re in the Type 1 zone.

Type 2 Fun, by contrast, is not fun. You embark on the quest for Type 2 Fun when you set out to attempt things that are deliberately hard. These often involve suffering, misery, fear, foul language and repeated vows never to do something this stupid ever again. Tremendous amounts of time and effort and commitment disappear into these endeavours. 

This is something that you are not doing for instant gratification. It is deeper, darker – and ultimately richer and more rewarding. Anyone who has run a marathon or completed a dissertation or assembled flatpack furniture knows about Type 2 Fun. Your version of Type 2 Fun might be very different to mine – appearing on stage in your first play, hosting a street party, coaching the U9s football team…

This is the world of doing something hard in the hope that at some unknown point, in an unknowable future, the endeavour will reward you with a sense of achievement, satisfaction, purpose and peace. Type 2 exploits will one day be a pleasure to recount over a poppadom and a pint. (A friendly word of caution: steer away from the pursuit of Type 3 Fun. Such activities are not fun. And they will never appear so in the future, no matter how warm the fireside reminiscences. The vows to never repeat anything so stupid hold firm even years later at last orders.)

Type 2 Fun is both an investment and a speculation. And it is often at the heart of the process of trying to live more adventurously. I encourage you – I dare you – to make the effort to toss a little more Type 2 Fun into your life. In my experience, while fun is fun, the more meaningful, enduring sensations of satisfaction and reward come through gritted teeth and Type 2 Fun. 

Writing this book, I have found it hard to set the tone and expectations appropriately. I am trying to champion small steps – a 5km parkrun before an ultramarathon, your first blog post before demanding a juicy advance from a publisher. But I also do not want this book to be an opt-out, an excuse for settling low or embracing mediocrity. 

I will always applaud excellence, ambition and ridiculous persistence. Start small, yes, but once you are up and running, you ought to be willing to suffer. Stretching yourself hurts, yes. But that is how you grow.

So if these pages have any whiff of elitism to them, let it be here. To champion effort and struggle and those who pour their heart into Type 2 fun, wading doggedly through the mud and storms to accomplish goals far beyond what you thought yourself capable of.