Across muscle-mincing gibber plains and sand dunes that sunk every step, the 24-year-old ran the 250-kilometre ultramarathon across the Simpson Desert earlier this month to raise funds and awareness for juvenile type one diabetes.

Finishing eighth overall, Mr Dernee said the challenge was one that pushed his limits and gave him a great sense of pride in his achievements.

"First day was great, no soreness. For an event like this, particularly being my first, it's hard to know if you're prepared or not but that's the point," Mr Dernee said.

"You don't need to spend time worrying about whether you're prepared or not you just have to get into it and embrace any surprising challenges or difficulties that arise, taking them in your stride so to speak."

Brutal yet beautiful, the desert was an uncompromising backdrop for the biggest challenge of his life.

"Overall the landscape had an ethereal beauty that can only be understood by spending days at a time in the Simpsons Desert," Mr Dernee said.

"It really is a marvel of a place with stunning sunsets and sunrises and amazing views once on top of the dunes."

Over the course of the run, Mr Dernee slept in a tent with two other runners.

Given the 14 kilogram weight limit for their gear , there was no room for bulky bedding, so he slept on a light, inflatable mattress, in a sleeping bag with a liner.

Mr Dernee said the hardest part of any day was peeling back the covers of his warm, protective sleeping bag every morning.

Food had to be non-perishable and made with only the use of hot water, so during the run, Mr Dernee ate a mix of dehydrated outdoor meals for dinner, and oats with sugar, peanut butter and dehydrated fruits for breakfast.

Lunch included noodles, cous cous, beef jerky, tuna and dehydrated fruits - fare you'd expect to find in a frat house, not necessarily the belly of an elite athlete.

To keep himself moving, he fuelled his body with electrolytes, water, trail mix and muesli bars.

On days one, two and three, Mr Dernee held his own with the frontrunners of the pack, finishing fourth, fifth and then fourth again respectively.

On day four though, disaster struck.

He was hit with an iliotibial band injury - severe knee pain for those of us who don't speak physiotherapist - which set him back in terms of running freedom, mind state, confidence and times.

"At the end of day three I was sitting well in fourth place but slid down to eighth with the slower times on day four and five," Mr Dernee said.

"Although I wasn't there to run good times or win, I was there to try and find just how hard I could go, just how much strength I had and find out what I'm made of.

"From that point of view the injury gave me a chance to test my resilience and, proudly, I came through it well and finished as best I could despite the increased pain when it could have been so easy to quit or walk the whole way."

He also sustained a number of blisters and bruised toes - the effect of running with shoes full of sand - and various aches, muscle pains and stiffness.

"Once the sand gets in [to your shoes] it's the equivalent of running with shoes a few sizes too big as the sand fills any vacant space)," Mr Dernee said.

"I've lost two toenails at last count and the ITB injury will likely take some time to recover and an absence from running for a few weeks."

Despite all this, Mr Dernee said throwing in the towel never crossed his mind.

"After 12 kilometres of the big day, I had very bad knee pain and walked for about 10 kilometres. At this stage I came to terms with the possibility of having to walk the whole way, however the time walking also gave me time to assess the reasons I took on this challenge to begin with, do some soul searching and get on with it," he said.

"I ended up running again, pushing through the pain and discomfort, running the second marathon 30 minutes quicker than the first and ran my fastest three kilometres of the 84-kilometre day at the very end after about 12 hours on my feet."

To push himself to keep going, Mr Dernee said he breaks it down to two options - to keep going or to quit.

"Quitting was never an option so once I broke it down to these options perseverance came naturally," Mr Dernee said.

"Anyone who runs a marathon whether it takes them two hours or eight hours achieves it the same way; by putting one foot after the other."

Now his massive run is over, he plans to hit the tarmac again as soon as he's recovered.

"I've got a few smaller runs coming up in the next few months with my first road marathon coming up in September," Mr Dernee said.

"Aside from that, as long as I keep loving to run, I'll be working running into my travels. There's a huge range of events in different fantastic locations around the world and in Australia that would be great including Nepal, the Whitsundays, Great Ocean Road, London and the list goes on but none of these are locked in as yet."

Currently sitting at just over $4,100 with fundraising open until September, there's still time to help Phill raise money in support of children with type-one diabetes.

Go to: https://bigredrun.everydayhero.com/au/philldernee.