It is raining, hard. It’s back during the New South Wales floods, and I can hardly see through the saturated sheets of water stinging my face. There isn’t a soul on the streets – no other halfwit is putting themselves through this deluge. But I have already missed two marathon training sessions this week and will not under any circumstances make it a terrible trifecta.

I arrived at my parents’ place for dinner, planning a tempo run before we eat. Inexplicably, my shoes did not arrive with me. So here I am, plodding in an old pair of my mum’s, akin to squelching weights around my ankles.

In any given week, there are runs which feel good, and others that are a labouring mess. This particular 55 minutes is fast falling into the latter category, and I can’t find the right song to solve the predicament.

I scroll Spotify and the slicked-wet touchscreen on my phone practically slips on to the Cure’s Close to Me. In purely mathematical terms, it is a winner – the ideal cadence is generally believed to be 180 beats a minute, and this upbeat number comes in at 185bpm with the added bonus of atmospheric background breathing.

Soon, something happens. My feet pick up, the rain metaphorically evaporates and I slide slowly, sweetly into a familiar parallel universe, an otherworldly zone where everything feels effortless, worries disappear and time ceases to exist.

Because time no longer exists, I am late for dinner, and promptly told to sit on a towel. But I have never been more content to marinate in rainwater and my own sweat, because I am high.

This euphoria is called “runner’s high”, and there is a physiological reason for it. Recent research has found the most likely type of bodily chemical responsible for the runner’s high are endocannabinoids, which work on the same brain receptors as THC, the active compound in cannabis. The longer the session, the more endocannabinoids released into the bloodstream. I am, quite literally, an addict. I realise it also makes me one of those irritating people who earnestly tells other, less irritating people, that they like running and actually means it.

I wasn’t always this way. As a young kid I was a walker in the school cross-country. I started running when I was 15 as an insecure teenager self-conscious about developing breasts. Soon, though, it wasn’t about that at all. As one lap of the block became 5km, and then 10km, I felt more alert and focused throughout the day. Stuff just felt … easier.

As an adult, it is necessary for my mental health. It can be the difference between a good day and a bad day, of not sweating the small stuff and stressing over every detail. For us introverted souls, it is blissfully solitary. If I miss a few days, the withdrawal symptoms are real.

The Japanese author Haruki Murakami writes in his book, What I Talk About When I Talk About Running, of his two decades of habitual long-distance running. His training logs double as observations, noting the methodical, economical style of endurance runners, the wordless smile or nod in solidarity with passersby, and the aggressive strides of a girls’ track team, their “proud ponytails swinging back and forth”.

How we all long to be proud swinging ponytails. In reality, most of us are unrefined shufflers. In terms of ability, I’m a middling amateur. My marathon PB – if one can call it that – is 3:46. My first was 3:57, only achieved thanks to a four-hour pacer. As the kilometres ticked by and tolerable pain became full-blown agony, a dwindling group of us huddled desperately close to him, waiting for him to tell us yet again that it was all in our heads.

Long runs call for mind tricks. One hour to go becomes 6x10 minutes, and 10 minutes equates to three songs. A symphony can be a decent soundtrack. An audiobook is a good distraction. Last week I listened to War Doctor by David Nott and reasoned that, if its subject matter was not happening to me, I could deal with some hip flexor soreness.

I have a love-hate relationship with marathons. I detest the actual act of completing the 42.2km, vowing to never again subject myself to such nonsense, but as soon as I cross the finish line am planning the next. All up, I’ve done four – two on roads and two on trails. The most beautiful was the Jungfrau marathon in the Swiss Alps, the most trying the Six Foot Track Marathon in the Blue Mountains.

I have spent years Googling “how to avoid hitting the wall”. This is one of many search terms – runners can get nerdy about details, dissecting everything from heart-rate thresholds to energy gels and stride mechanics.

It can border on obsession. Runners are chasing the high, and will do whatever it takes for the next hit. Even it means boring gym work to prevent injuries, and treatment when you get them anyway.

A few years ago I fell and shattered the bones in my elbow. As the surgeon wheeled me into theatre, he said I may never again have full movement in my right arm. I drifted into unconsciousness feeling content in the knowledge it wasn’t a leg.

My legs are a conduit for experience. Each time I visit a new city or country I run. I have run around Cairo, Kampala, Kathmandu, Rio, Delhi, Hanoi, Muscat, New York, and more spots in Europe than I can count. It is a chance to inhale local smells and absorb a culture from unexpected angles.

At home, part of the joy is the novelty of pushing myself, the inherent satisfaction in bringing yourself to the brink of spewing and never feeling so alive for it.

Lots of runners train to race. I train simply to train, and use the goal of a race to make me do it. It is both pleasure and pain, success and failure, exhilaration and tedium. There are times I wish I had never started. But now I am an addict, and will never stop.