I know I shouldn't think about it, I'll scare myself to death but after 17 hours in the air, I can't get the worst case scenario out of my head.
No, not a plane crash. I'm convinced that I am breathing more farts than air.
I'm on Qantas' inaugural Perth to London flight, the longest to and from the UK, and the atmosphere in the pressurised tube I've been sharing with over 200 other bodies has gotten quite stale.
And while I'm not the only journalist on the flight, I am the only one who has been sat in economy for the 14,498km journey.
Sadly for me, "Intrepid Travel Writer Survives 17 Hours In Bed" is not much of a story.
So while a gaggle of excited Australian press turn left into a world of champagne and lie-flat "suite" beds, I venture right, into the familiar kingdom of screaming kids and aching bottoms.
Qantas' new daily route between the UK and Australia means holidaymakers between the two countries can now avoid the time-consuming hassle of a transfer in cities such as Dubai, Singapore or Hong Kong.
But is shaving a couple of hours off your journey really worth taking on the all-new endurance sport of extreme long-haul flying?
The first London to Perth route was scheduled to take 16 hours 45 minutes, while my inaugural inbound journey, going against the wind, took around 17 hours and 15 minutes.
But between taxiing, boarding and disembarking, my time spent on board leapt to almost 18 hours.
I boarded flight QF9 in Perth just after sunset and we took off on time at 6.50pm. Flying away from the sunrise, we wouldn't touch down again until well before daybreak at 5.03am the next day in London.
In total darkness for the entire journey, the route is not only the UK's longest but also holds the depressing honour of being the world's longest flight without daylight.
Before takeoff we were given strict instructions over the tannoy: "For your safety, we do not allow anyone to sleep on the floor."
You know it's going to be a tough flight when they're worried about passengers lying in the aisle in a desperate bid to get some shut-eye.
Unable to use the Qantas app to check in, I was saved the misery of my allocated middle seat by my seat-neighbour Emma Hodge, a regional manager from Devon, UK, who wanted to sit with her boyfriend, leaving me the aisle seat.
When I asked what on earth made them book the flight Emma explained: "We didn't. We were supposed to be flying Melbourne via Dubai but they shunted us onto this route instead."
She continued: "I'm a nervous flyer, but despite two-and-a-half hours on the phone with the airline, they wouldn't even let us keep our seats next to each other."
Not the ideal place for a fear of flying, the west coast of Australia can brew up some nasty storms.
We couldn't be served so much as a glass of water for the first hour as the cabin crew were seat-bound while we were bounced about by a Tropical Cyclone called Marcus.
So if not sleep, what are customers to do for 18 hours straight?
There's time to binge all the way to episode two, season three of Breaking Bad, watch eight Star Wars or Harry Potter films, see Crocodile Dundee 10 times, or listen to every Beatles track nearly twice.
The in-flight entertainment had an average, if a strangely festive catalogue, for a flight in late March. I don't know how bored you need to be to watch A Bad Moms Christmas starring Mila Kunis, but somehow I never quite got there.
At the eight-hour mark, back aching, I reached for my mobile only to realise this was probably the longest time I'd been away from the internet since the noughties when I swapped my Nokia 3210 for an iPhone 3G.
Incredibly, for the launch of such a mammoth route, Qantas' shiny new Boeing 787-9 Dreamliner doesn't offer Wi-Fi — although they promise it's coming.
Besides the missing web connection — presumably, someone forgot to install the SIM card — I'm a fan of the plane and its eerily quiet cabins.
However, the noisy hum of an old Airbus had its benefits when it came to privacy.
Hearing fellow passengers' conversations as clearly as if they were sat on your lap, adds a new level of claustrophobia to the nervous act of perching on an aeroplane loo. Shy pooers need not apply.
It's the fuel efficiency of the Dreamliner that has made ultra long-haul routes like this not only possible, but Qantas hope, profitable and the airline has plans to one day launch London to Sydney direct, a journey that would take over twenty hours.
The Dreamliner may not be a gas-guzzler, but a layover is nearly as environmentally friendly, especially via Dubai or Qatar, which both lie directly on the route to Perth.
A long flight means carrying more fuel, adding weight to the plane, which in turn means burning more fuel.
One thing that's light on board is the food, which began three hours in with a bread roll, chicken with rice and veg, followed by a mango and passionfruit pannacotta.
Designed especially by nutrition boffins at the University of Sydney, it was painfully bland but meant to help keep you hydrated, something you'll want if you're going to make the most of the drinks trolley.
When the kangaroo route first opened in 1947, British holiday-makers hoping to see Australia had to make seven stops over four days, but it's yet to be seen if consumers will embrace bringing the number of stops down to nil.
Passengers will be paying a premium for the direct route, and there are signs that consumers are yet to be convinced. Despite it being the inaugural flight, with first class full of media (including four TV crews) and economy full of flight anoraks, there were 23 seats left free in economy and one in premium.
At around the 12-hour mark, with over five hours to go, I finally managed to fall into a cramp-filled slumber before waking up for a classic airline breakfast of soggy sausage and bacon, omelette beans, cake and yoghurt.
Like an archaeologist prizing open the sealed tomb of some long-dead Pharaoh, airport ground crew are often hit in the face by a primaeval gust of rancid air when the plane door swings open following a long-haul flight.
After nearly 18 hours, I'd imagine ours was enough to knock a couple of Heathrow's bravest clean out.
On disembarking, I was groggy, aching and ready for bed, but that's exactly how I'd feel after any long-haul journey over eight hours. At a certain point, you just embrace the confinement and try to enjoy the ride.
Brits looking to book a holiday in Australia should, by all means, kick things off on the west coast, it's a beautiful part of the world.
But travellers on a budget will find a one-stop double-hop might still be the smarter choice for trips between Australia and the UK.
Flight comparison site Skyscanner found direct return flights for 2018 with Qantas cost from $1400 return, while return flights in 2018 with a layover of under two hours are from just $1050, stopping in Abu Dhabi with Etihad Airways.