I’VE always been told not to sweat the small stuff. But when you are the small stuff, even in a room full of dust mites, it’s difficult to find things not to perspire about.

If you’ve ever known anxiety, you’ll recognise that little becomes large more often than in my Syd and Eddie fever dreams. Those stupid things that matter as much as a split atom somehow swell to full Eat Me proportions in an adrenaline-soaked brain. You can’t fight or flight a desk change at work so sometimes fright is the only available response. And, most days, it’s more available than a Tinder Top Ten.

For a long time, I was the foreman of my own mental demolition, with more effect than a bucket-load of Acme produce and giving the most innocuous experiences the power to push the plunger.

Answering the phone became an exercise in damage limitation, with a projected blast radius of which Faslane would be proud. Not to mention the terrors of public transport – well, except to base this column in its entirety upon them. Tackling a train journey single-handedly has always brought about my own derailment. This week then, I decided to tackle one single-mindedly instead, with the help of the Great City Swap.

If you’ve wandered down Glasgow’s Buchanan Street or Edinburgh’s St. Andrew Square recently, you could be forgiven for thinking Thomas and his friends had gone slightly off track. Fear not, ferroequinologists, the Fat Controller has not lost his wits along with his bulk; the iron horse that gallops our cities’ cobbles is actually ScotRail’s inaugural Swap-A-Tron – obviously. As part of their Great City Swap promotion, to encourage the home-bodies of Scotland’s east and west coasts to strap on their braces and cross the central belt for a day, ScotRail have left the concourses to bring a bespoke itinerary selector to the streets.

Now, I’m a Glaswegian from salty core to vinegar seasoning, and my compass spins the moment I pass Coatbridge, but that’s where the Swap-A-Tron enters stage right with an updated plot-line.

I joined the Great City Swappers on Buchanan Street on Wednesday morning to meet Nicki – spelled like Minaj – who, wearing eight layers of insulation, had been on hand since the beginning of the week to take day-trippers through the Swap-A-Tron system. Armed with a tablet and a penchant for rejection, Nicki took me and anyone with a free afternoon and an adventurous spirit into a world of the arts, of the undiscovered, and of, well, the shopping, if that’s your thing.

Easier to navigate than the Outer Circle, the Swap-A-Tron gives commuters computers to input their age range, interests and chosen date, and promptly flashes up a customised programme of activities based on your preferences. So, if the output sucks, basically, you need to take a look at your life choices.

For the more daring – or indecisive – travellers, there’s also the option to let fate decide your schedule. Of course, the randomiser was my go-to button, safe in the knowledge that the software has tolerance built in, allowing the most exacting of users a do-over if the results aren’t quite as hoped.

Within minutes, I’d been emailed an agenda of things to do and places to dine, since no Scottish day out is complete without at least one fried course. And for train virgins – or at least, ingénues, like myself – the recommendations come complete with details of the best ticket type for the trip, including a Kids Go Free ticket for anyone travelling with an under-16.

Off I set for a day in the capital, on my own, but feeling somehow still in safe hands. The nerves kicked in as my feet hit the platform at Queen Street station, but forewarned, as they say, is fore-armed and I had good counsel in my holster, reminding me exactly what to ask for and where best to go. And, you know what, it really helped.

Flutters aside, I took a seat, unsure of the reservation protocol, and spent 10 minutes avoiding eye contact with pausing passengers whose place I might or might not have taken. That apart, the journey was nigh-on relaxing. Even during one slight panic when I realised there’s more than one station in Edinburgh and I don’t know my way around any, the rhythm and control of the tracks brought me to calm.

At the Swap-A-Tron’s suggestion, my first visit on arrival was to the Scott Monument – Gothic, striking instantly recognisable, and unbeknownst to this ignoramus, entirely climbable, with four levels across its 287 steps from which to view the city’s undeniable charms.

Onwards on my cultural excursion, I headed to the National Museum of Scotland, to wander in wonder around the Wildlife Photographer of the Year exhibition’s visit from London.

On this one, the Swap-A-Tron hit the nail on the donkey for me, as each of the 100 award-winning images danced on my retina and rested on my mind.

With a quick stop in at Eteaket tearoom for a proper cuppa and maybe just a sliver of the sweet stuff in perfectly primped surroundings, my city swap was all but done and, genuinely, it was great.

Maybe I could have jumped out of another plane this week, or scaled another mountain, but I felt particularly proud on that solitary train ride home because this somewhat low-key adventure was still a huge step in my own life’s journey.

The Swap-A-Tron will be available on-street until 6pm tomorrow, and online until November 11 at www.greatcityswap.co.uk