Why climb a mountain? Don’t say “Because it’s there.” It’s said that when the great, doomed mountaineer George Mallory used the phrase in 1923 it was uttered dismissively, without the gravitas it later gained. Just because climbing a mountain may serve no obvious practical purpose, there are plenty of better reasons to get to its summit than its mere existence. Far better.

I didn’t walk to the top of anything high until I was 20, when I was dragged. Until then – as with many people who look overseas rather than exploring their own backyard – I was considering emigrating, to Canada. I believed the nonsense about Britain being a claustrophobic place where you could never find the crystalline magnificence you visualise when you think of escape, wilderness and all that stuff.

Then that day I climbed Skiddaw, in the Lake District, I saw layers of blue mountains spilling from my feet, only 1½ hours from where I’d lived all of my life, and realised I’d been missing something. In 2004, I took a job on Trail magazine (which I now edit), and learned two things quickly: the more you see of Britain, the bigger Britain gets; and you haven’t seen it at all until you’ve seen it from a mountain.

So first, get it out of your head that a mountain is a thing. A bollard is a thing. Mountains are places. Things are just there. But in places, things happen. They appear on maps, cover ground, create weather and bear life.

Our ancient peoples saw them as the homes of gods and monsters. Our greatest poets found muses in them. They’ve harboured scientists, smugglers, occultists and ghost hunters. They were, and are, uninhabited, inhospitable islands of wild. Agriculturally barren and obstinate to passage, mountains are the last landscapes to become useful, and so are left to the fringes.

And being the wonderful geological hotchpotch Britain is, you don’t have to travel far to feel a complete shift in the way the mountains cut their dash. There is true variety here: the volcanic summits of the Cuillin ridge on the Isle of Skye; the strange, free-standing peaks of Assynt, north-west Scotland, eulogised by poet Norman MacCaig; the exquisite tapestry of mountains, lakes and slate villages of the Lake District that were such an inspiration for Turner, Wordsworth, Ruskin and Coleridge; Snowdonia, with its Tolkeinian mines, climbs and folk tales – all underpinned by its splintered mountains …

The most wonderful attribute of all of these is their scale. They can all be explored on foot, mostly in a weekend. Leave London – or other cities en route – by sleeper train on a Friday night and you’ll wake up in the Highlands on Saturday morning. A flight covers the distance between London and Inverness quicker than you can cross London by tube.

Once in the uplands, you can have a real adventure with few of the collateral hazards of other mountain areas. You can camp safe in the knowledge that no animals will pull you shrieking from your tent into the night. You won’t get altitude sickness. You’re never more than 10 miles from a road. There are no crevasses to fall into, no deserts to get lost in or hostile tribes to be wary of. And there’s so much freedom here: in many countries, you keep out unless told otherwise. Thanks to the right to roam, in most parts of Britain it’s the other way around.

That said, our mountains do have teeth. That old joke about Everest being good training for the Highlands of Scotland is only funny if you’ve never experienced the Cairngorms in winter, or looked up at Snowdon’s sharp summit when it’s white. It’s alarming how extreme Britain can be: the first taste of this engenders a mixture of sudden, shocked respect. Chuck it in the deep freeze and suddenly, electrifyingly, Britain stops playing nice.

But you’ll come to crave the feelings. The chill, the silence and the space. The darkest night you’ve ever seen from the window of a stove-lit bothy. The tired-happy exhilaration of being a mile high having walked there. The thrill of holding on for your life, and living. Of swinging a bag on to your back that contains all you need to sustain yourself, then doing it. The act of boiling life down to the basics – get up, move, eat, sleep, get down – is the ultimate in perspective realignment. And the few who make the effort to get into Britain’s wild rafters share the biggest secret of all: up above the millions in this crowded … this apparently suffocatingly crowded nation, the spaciousness and enormity is breathtaking.

“Because it’s there” is the last reason to climb a mountain. Perhaps another of George Mallory’s comments carries more truth: “What we get from this adventure is sheer joy. And joy is, after all, the end of life.” Everest, Helvellyn, Snowdon, Ben Nevis. To those who know, that joy inhabits the same lofty step – where the mountains of Britain stand as tall as any in the world. One of Mallory’s gifts to Everest was to name its great valley the Western Cwm, a Welsh word, because it reminded the mountaineer of Snowdon.

Mallory’s mentor was another mountaineer-philosopher, Geoffrey Winthrop Young. A line from his poem, A Hill, about the implacability of the British mountains’ lure, gave me a title for my book about the same:

Only a hill, but all of life to me,
Up there between the sunset and the sea

So, why climb a mountain? Stop asking. Just climb one.

• Simon Ingram is the author of Between the Sunset and the Sea (HarperCollins). To order a copy for £7.99, including UK p&p, visit bookshop.theguardian.com or call on 0330 333 6846. Simon is the editor of Trail, the UK’s bestselling hillwalking magazine. For a free digital issue of Trail click here

The caption relating to Skiddaw in the Lake District was amended on 14 June to reflect the fact that the fells pictured are part of the Skiddaw range. Skiddaw itself is just out of shot, as some commenters have pointed out.