With his twenties all but over, our columnist looks back on a decade of opportunities squandered – and attempts to make some last-minute amends .

It was the summer of 2009. I was 22 years old. I’d been invited to an all-night “bacchanal” organised by the Piers Gaveston Society, a debauched drinking club run by posh Oxford University students that’s best known for a scurrilous, but hilarious, tabloid rumour involving a now ex-prime minister and a dead pig’s head. Look, just google it.

The event was staged on a grassy field in the shadow of a stately home. Cans of Strongbow and Red Stripe bobbed away in black plastic bins full of water. A man in a kaftan – I think he was called Finbar – roamed the site offering tabs of acid and plastic capsules of so-called “research chemicals” to eager freshmen. The distant throb of goa trance and fidget house emanated from a marquee somewhere in the distance.

Night fell. By the orange glow of a bonfire, a beautiful girl approached me and asked if I’d like to frolic with her in the woods at dawn. “OK,” I said, thinking that frolicking in the woods at dawn seemed like exactly the sort of thing one should be doing at an event such as this. She smiled and, without saying another word, wandered off into the night.

Dawn arrived, imperceptibly at first. As the sun slowly rose behind thick layers of cloud, casting the field in a pale blue light, I began to notice for the first time just how cold it was. The girl I’d met last night tapped me gently on the arm. She was still beautiful. Even more so with mascara and glitter smudged across her face. But the dawn I’d imagined – a low mist, scraps of cloud in dove-grey, peach and cotton-candy pink, a sliver of golden sun peeking above the horizon; something Mr Claude Lorrain or Mr Jan Both might have painted, only transplanted to regional Oxfordshire – had singularly failed to materialise.

“Shall we go?” she asked, lacing her fingers through mine. I looked up at the whitening sky, over at the dull scrap of trees that had, last night, seemed so inviting, and down at the crushed Strongbow cans scattered on the grass. Then I said something I have regretted ever since.

“Nah. You’re all right. I think I’ll just get the bus.”

Why? I’ve asked myself that question several times over the years. Because I was young, I guess, and I had impossibly high standards when it came to sunrises. Because I knew there’d always be another girl, another party. Because suddenly, in the cold light of day, frolicking in the woods at dawn seemed like a terribly clichéd thing to do.

Something you should know about me is that I’m cool. Or, at least, I try very hard to be. I’ve spent the whole of my twenties trying. And if there’s one thing I’ve learnt, it’s that it isn’t a great way to have fun. Six years ago, I queued up three times to get into Berghain, a Berlin techno club that, in the grand tradition of Studio 54, maintains its aura of cool by letting in only guests who look like they don’t especially want to be there. I’m fairly sure they only let me in third time around because, by that point, I genuinely didn’t.

The summer after that, I spent an interminable three hours watching 2001: A Space Odyssey at a pop-up cinema under the A12 flyover in Hackney Wick. I discovered later that the people responsible, a design collective called Assemble, had gone on to win the Turner Prize, an annual accolade awarded for Britain’s most challenging piece of conceptual art. I can’t say I was surprised. There was definitely something challenging and conceptual about a cinema whose sound system was completely drowned out by the rumble of lorries passing overhead and whose wooden seats couldn’t decide whether to give you splinters or haemorrhoids, or both.

Central to the idea of cool, of course, is the rejection of everything mainstream or clichéd. Practically speaking, this means saying no to a great number of things. Hot new restaurant opened up next door? Terribly sorry, but it was featured in Time Out last week and now I wouldn’t be seen dead there. Free tickets to a gig? Great! Who’s playing? Mumford & Sons. Ah. Might have to give that one a miss after all. I wonder, though, as I look back on a decade of relentlessly chasing the zeitgeist, just how many experiences I’ve denied myself because they didn’t quite fit my preconceived, millennial, Campari-in-a-car-park definition of an aspirational lifestyle. Has my carefully curated social life been nothing more than a catalogue of missed opportunities?

The last summer of my twenties is already well under way. I turn 30 in September, and while I retain a Joycean dreamer’s instinct to wake up early one morning and walk westwards for ever, travelling around in front of the sun, never technically growing a day older, I know this is one that I can’t outrun. That’s why, in a possibly self-destructive act, I’ve decided to stop saying no and start saying yes. To live deeply and suck all of the marrow out of life. For the rest of the summer, I’ve pledged to say yes to everything – every party, every Facebook event.

It’s a risky business, though. As I write this, I’m reminded of an old friend who, while at university, was coerced into attending a naked rave. “It’ll be so spiritual,” they told him. “So utopian.” And so, with a coterie of liberally minded friends, he put wildflowers in his hair, painted his face with glowstick juice, as was the fashion at the time, donned a dressing gown and took the bus from Oxford to a little place called Vauxhall in south London. I found him in the kitchen the next day, standing at the sink, furiously scrubbing dishes with Lady Macbeth’s “what, will these hands ne’er be clean?” expression etched across his face. He never spoke about what happened that night, but you didn’t need to be a regular patron of the Vauxhall club scene to conclude that it wasn’t quite the midsummer night’s dream they were looking for.

So far, things are going rather better for me. Already, I’ve signed up for a marathon on the west coast of Ireland, in a small fishing village called Dingle. It is both tremendously exciting and entirely inconvenient. I should probably be training right now, but I’m busy writing this column from the chill-out tent of Secret Garden Party. It’s a festival I’ve rejected the offer of attending several times before, mainly on the basis of its irritating name. There’s nothing secret about it, for a start. It has an easily accessible and highly informative website. And it’s not in a garden, either. It’s on a farm. I guess the name Well-Publicised Farm Party was already taken.

Despite my pedantic gripes, I’m having quite a good time. Who knew? I think I might go and find some woods to frolic in. Whatever frolic means. How does one frolic? I should have figured this out a long time ago.