How I’m Training For My First 100 Mile Run

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When I wrote the article Why I’m Running 100 Miles back in mid-September, I was nestled in the window seat of a plane carving a route from Milan to Barcelona.

I had spent a long summer traveling around the mountains, working on farms, and meeting people whose lives were so different from my own. And as I watched the sunset stretch endlessly over the Mediterranean sea, I was filled with intense enthusiasm for life and for my insane goal of running 100 miles. I typed without pause.

In the article, I detailed how I love to seek discomfort, how I feel like I’m addicted to running, and how inspiring it is to have a goal so big.

Since then, I weaved my way up through Spain, and then France, and eventually, come October, I was settling down for winter in my hometown on the south coast of England.

And since then, my late summer enthusiasm, and the time I have spent running, have significantly dwindled. I am writing this on Boxing day, and I am due to toe the line of the 100-mile race in just over a month’s time.

There are no two ways about it, I am majorly undertrained.

I could list excuses, but none of them would hold up in court. I think it boils down to how uninspiring it is to be in England over winter. Regardless, I have (in a roundabout way) trained for the mammoth task that lies ahead of me.

In this article, I’m going to break down what my training has looked like over the last 6 months, including:

  • Physical Training, including leg training and gut training
  • How my Lifestyle has changed to support my big run
  • Mental Training, including visualisation, self belief, and learning
How I'm Training For My First 100 Mile Run 1
(This sunset made me cry)

Physical Training

Something that you shouldn’t be skimping on.

Training my legs

Please do not do what I did.

As I neared the end of my first ultramarathon, a 100k race, and my thighs buckled on every gentle downhill, I vowed to myself that my next training block would include lots of strength training.

Have I strength trained this time around? About twice…

However, it’s not all bad news for my legs. This past year has been my highest mileage year ever. In 2021, according to Strava, I ran a grand total of 2598 km (1614 miles). Albeit, most of those miles were logged in the first half of the year.

I know that to the experienced ultrarunner, 2600 km may not seem like much. But regardless, I feel that my legs have put in a decent shift.

How I'm Training For My First 100 Mile Run 2
(The reality of running through a British winter)

Training my gut

It turns out that GI related issues are one of the main reasons runners DNF during an ultramarathon. It’s no surprise seeing as you have to eat between 5000 and 7000 calories during a 100 miler.

Luckily, I’ve never had much of an issue with eating on the fly, (apart from when I accepted a slice of orange from a well-meaning spectator at my first marathon), but I really don’t want gut issues to be the reason I don’t finish the 100 miler.

So to train the gut, I really messed with it (I’m not sure this is the right approach, so don’t do as I did). I would go for some runs on an empty stomach, others straight after eating a big meal, on some long runs I would barely eat, and on others, I would eat incessantly.

The types of food I would eat as I ran varied wildly from sweets to sandwiches, to homemade cereal bars, to cake, to potatoes, to fruit, to stopping for a cafe meal mid-way through a run.

All of this chaotic gut activity has made my stomach pretty resilient. I’m certain I could eat anything (apart from citrus fruit) on a run and be ok.

How I'm Training For My First 100 Mile Run 3
(Potatoes became my favorite mid-run snack)

I will say, sweets, sports drinks, and gels kind of suck. I can eat them, but I’ve found that the energy they give me almost feels fake. If I pop a handful of sweets at the bottom of a hill, it will take me to the top, but not much further. It feels like putting paper on the fire instead of wood. I’ll be using them as a pick-me-up if things are horrible.

For good gut training advice check out these articles (and do as I say, not as I do!):


For me, it boils down to this: minimize stressors, eat lots, sleep lots, don’t smoke, don’t drink lots of alcohol.

For a massive physical challenge, I’m a firm believer that you have to get your lifestyle in check.

How I'm Training For My First 100 Mile Run 4
(Running has made me deeply appreciate trees)

I live very close to London. I have a bunch of friends who live there, and a weekend out and about in The Big Smoke is always a good time, but I haven’t made a habit of it.

Instead, over the last few months, I’ve chosen to spend my money on a holistic running physio, Mark. He watched me run up and down the street, poked around in my stomach, pulled on my toes, and made me hop from one foot to the other.

Mark set me some homework: early bedtimes, Yin Yoga, The Wim Hof Method, Earthing, knees over toes exercises, Buteyko Breathing, and reminding myself to feel the ground under my feet and to relax my tense core.

I’ve dabbled in Mark’s advice and it’s been fun. I’ve chosen to live a more intentionally healthy life over the past few months.

Training for 100 miles is a massive undertaking for the body. I think that it would almost be cruel to yourself if you were to take on such a huge endurance challenge without supporting your body with a healthy lifestyle. It would be like trying to grow a sequoia tree in barren soil.

How I'm Training For My First 100 Mile Run 5

Mental Training

This, in my opinion, is by far the most important part of ultra training. And it is also, thankfully, the part that I feel best prepared for.

Arming myself with knowledge

I think that knowing what you’re getting yourself in for is a good idea. You know they are coming, so you are better prepared to handle the inevitable obstacles.

I spent the last few months studying for my UESCA Ultrarunning Coach Certification. This for sure armed me with a lot of really useful knowledge.

I also read up on all things endurance biology. I researched the psychology of pain, the mind-body connection, and read Alex Hutchinson‘s book Endure about the Curiously Elastic Limits of Human Performance.

I read Michael Crawley‘s Out of Thin Air about the magic and wisdom of Ethiopian runners.

Self Belief

One aspect of mental training that I’ve found very useful when doing big things is the unwavering belief that I can do it.

I think that I’ve developed this outrageous self belief by faking it until I believed it. When people ask me if I think I can actually do that hard thing I’ve set myself, I make a point of always saying yes, even if I do have doubts.

What I believe this does is allow for the possibility of being able to complete it. If I were to hmm and haa about whether I could, I would be strengthening that part of my brain that doesn’t believe I could do it. Instead, I choose not to feed it with uncertainty.

I practice being headstrong in my self belief when things are easy- when I’m just going about my day, chatting with friends, doing training runs. So that when it counts, when I’m in mile 90, I have more of that to cling on to.

If I were to doubt myself when things are easy, I don’t believe there’s any way I would have the mental strength to keep going when things are hard.

How I'm Training For My First 100 Mile Run 6
(A view from one of my regular running routes)


I’m a big fan of daydreaming, so this one does come easy. I invent scenarios in my head of the difficulties I may face during my 100 miler, and I imagine myself moving through them.

Here’s one scenario that keeps coming back to me:

It’s the middle of the night and I’ve been running for 20 hours. It’s raining hard and I’m battling a powerful headwind. I shuffle into an aid station, I can barely say a word, I grab some snacks and water, and turn my back on the familiar warmth of my family and the promise of a bed to trudge up a muddy hill and into the unknown darkness of the Yorkshire Dales.

I feel like this scene captures the most challenging aspects of a 100 miler, so I keep replaying it to myself.

will it be enough?

I am genuinely very intrigued as to whether what I’ve done will carry me the full 100 mile distance.

Will the next 100 mile article I write be titled ‘I DNF’d My First 100 Miler’? Or ’10 Things I Learned From My First 100 Miler’?

Regardless, I am going to send this piece of writing over to Coach Thomas, who will then publish it for all the world to see.

why am I doing this?

Good question! Here’s my attempt to answer it:

Photo of author
Maria Andrews is a runner, adventure lover, and UESCA certified Ultramarathon Coach. When she's not running around the woods or plotting adventures, she's spending time with her nearest and dearest, cooking up a storm, or working on Marathon Handbook's sister website, yogajala.com :)

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