Legs like concrete. Lungs on fire. Physically drained. Mentally distraught. And yet, there are still five miles of pure torture until the pain is over.
Every step feels like running in mud. The breathing gets heavier and heavier. The tiniest of inclines look more like Mount Everest. Morale support feels like an insult.
Then, there it is, the sight of all sights - the finish line. There's no glossing over the brutality of marathon running, which makes Eliud Kipchoge's attempt at history on Saturday all the more jaw-dropping.
And, after pushing my body beyond its limits at the Baxters Loch Ness Marathon last Sunday, I'd like to think I can relate - albeit very loosely - to the Kenyan icon when he mounts his remarkable attempt to become the first-ever runner to break the sub two-hour marathon.
The comparisons between myself and Kipchoge, 34, arguably start and end with the fact we both enjoy running and get some sort of bizarre thrill out of putting our bodies through physical and mental distress.
For me, the 2016 Olympic marathon gold medallist's quest to achieve history on Saturday is even more compelling after completing my third marathon distance less than seven days ago.
It was tough. I was carrying an injury into race day, which prevented me from getting any serious mileage under my belt for more than a month, and the hills took more out of me than ever anticipated.
It wasn't all blood, sweat and tears though, and as routes go, this one is among the best in the world (just look at the backdrop...).
With spectacular scenery that takes you alongside the world famous Loch Ness and through the stunning Highland forests, there's plenty to take your mind off the pain.
And when you throw a carnival-like atmosphere into the mix - plus thousands of like-minded wannabe athletes all in a similar predicament - it's easy to see why this event is growing in numbers every year.
But, as a runner, one minute you're able to enjoy the bucket-list scenery. The next minute you're back to square one, wondering how you're ever going to get to the end. That's what marathon running does to you.
I began to hit the much-feared 'wall' around mile 16 and for the last five miles, it was a never-ending slog to the finish line, which I eventually crossed in three hours 24 minutes to register my second-quickest time.
So, the fact Kipchoge is attempting to run a marathon in a whopping 1.59 - or quicker - is just out of this world.
And it also explains why he believes this quest, dubbed as ‘INEOS 1:59 Challenge’, would be comparable in the annals of human achievement to standing on the moon or scaling Everest for the first time.
"[Breaking the two-hour barrier] is like stepping on the moon, going up the tallest mountain and even going to the middle of the ocean," said Kipchoge.
This attempt will take place in the Prater park in the Austrian capital of Vienna on Saturday, with Kipchoge running laps of a flat 9.6km course that includes two 4.3km stretches.
The 34-year-old ran 2:00.25 in his previous non-world record attempt in Italy in 2017 - the Breaking2 project - and immediately made it his target to finally achieve what would be a sporting miracle.
In order to make history in the 26.2-mile distance, Kipchoge is required to sustain a pace of four minutes and 35 seconds a mile for more than 26 miles.
And there I was thinking my Loch Ness pace, an average of seven minutes 50 seconds, was respectable...
For those not that familiar with minutes-per-mile pace, the Kenyan will be running on average at around 13.1mph to beat the sub-two mission - meaning he could keep up, perhaps even beat, most central London traffic.
Still getting your head around it? Well, imagine getting on a treadmill, setting it to 20km (level 20 on most gym treadmills) then running non-stop for two hours. That is what Kipchoge is attempting to do this weekend.
The reality is: he boasts superhuman talents that enable him to push the running boundaries like no other, and the stats back that up.
Kipchoge holds the official world 26.2 mile record of two hours, 1.39 minutes set in the Berlin Marathon last year, and ran the second-fastest time in history when winning the London marathon in 2:02.37 in April.
But his 2:00.25 Monza time in 2017 is not recognised as it was achieved using “in and out pacemakers”, was not an official race and he was given mid-race drinks from a moving motorbike rather than having to collect them from a roadside table.
And again in Austria this weekend, the tailor-made nature of this programme means his time - whether or not he makes history - will not be recognised by the International Association of Athletics Federations (IAAF).
That is because human intervention will once again help him in his attempt to achieve his dream.
Kipchoge will have 41 elite pacemakers to assist him, including Ethiopia’s Selemon Barega, who won the 5,000 metres silver medal at the Doha championships this month, Uganda’s Ronald Musagala, the two-time Diamond League 1,500m winner in 2019, and Olympic 1,500m champion Matthew Centrowitz of United States.
The pacers have been practising in various formations to best protect Kipchoge from the wind and they will be swapped in for three or six-mile sections as they cannot keep pace with the record bidder.
There will also be a pacer car - set 20 yards ahead of the Kenyan – which will beam a fluorescent green laser onto the road to display where he needs to be to make history.
It is predicted that the car will be 10 or 20 seconds ahead of the required pace, so even if Kipchoge has a minor setback or hiccup, he should still be ahead with enough time to spare to get across the line in under two hours.
There are other variables to consider too, like Nike's high-tech ZoomX Vaporfly NEXT% shoe, which cost at least £240 and boast a carbon fibre plate which ultimately reduces the load on the calves.
How I could have done with those in Scotland... Having said that, the shoe that Nike says improve running economy by up to four per cent is not without controversy.
The shoes have been passed legal by the sport’s governing body the IAAF, though some critics say they give such an advantage that without them Kipchoge would be a “routine” 2.03/04 performer.
But that's not to take anything away from Kipchoge and his attempt to cement his name further in long-distance folklore.
When he lowered the legal world record in Berlin last year, he did so by an astonishing 78 seconds, while his amazing record of 11 wins from 12 races over the 26.2 mile distance speaks volumes too.
The pacers won't prevent his legs from feeling like concrete. The car won't make those self-doubts disappear. And the trainers certainly won't stop his lungs from burning.
Marathon running is the ultimate battle, both physically and mentally.
My Loch Ness Marathon - and I'd like to clarify that I'm a relatively-accomplished runner with a respectable PB of three hours, 11 minutes - was the perfect example of the barriers you overcome to drag your body through 26.2 miles of hell.
Kipchoge is taking long-distance running to new heights few knew ever existed. He deserves to take his first step onto the moon.
Early bird entry for the 2020 Baxters Loch Ness Marathon and Festival of Running, which takes place on 4th October is now open. Sign up for the 2020 races at www.lochnessmarathon.com
