RUNNING A MARATHON WILL BE ONE OF THE GREATEST THINGS YOU EVER DO – TRUST ME, I’VE COMPLETED 10

Published: 22/01/2026 | By: Ally Head

Ever wondered what it’s really like to run a marathon? Marie Claire’s Editor and ten-time marathoner Ally Head takes you behind the scenes – the sweat, the doubt, the tiny victories, and that incredible moment crossing the finish line. Whether you’re curious or thinking “I could never do that,” this guide shows anyone can tackle 26.2 miles and come out stronger (and maybe even a little addicted!).

Drums bang, horns blare, and strangers scream your name from every direction. The sound of the crowds – at least five people deep, on both sides of the road – is deafening. Kids sit on shoulders. Friends hang banners from bridges. Crews blast confetti cannons. You didn’t know it was humanly possible for your legs to hurt this much. But you keep moving forward. One step at a time. Left foot, right foot, repeat. You’ve nearly made it – you're 400 m from completing your first marathon.

The most random thoughts seem to loop around in your head. Is your big toe going to fall off? Why is your bra chafing so much? Is it possible to drink too much water? Blood pumping, heart racing, it’s taking every ounce of your being to put one foot in front of the other. Count down from 200, you keep telling yourself. 200. 199. 198… 350 metres to go. Nearly there.

You turn the corner onto the mall and can’t stop the grin from spreading across your face – despite the 24-degree heat. You can see the finish line – royal, regal red, inviting you to cross it. 41,945 meters down – 250 to go. Over the tannoy, the race commentator spurs you on. “You’ve nearly made it! You’re all heroes! You’ve achieved what only 1 % of the population ever will!”

Emptying the tank for a final minute, and eighteen weeks of emotion – of early morning training runs, of saying no to social plans, and of doubting whether you’re actually cut out for a challenge like this – streams down your face in the form of fat, happy tears. The feeling is indescribable. Sheer joy, utter elation, and instant relief. Gratitude for your body, gratitude for your mind, and gratitude for the fact that you’re no longer running and can finally sit down, weighty, well-earned medal hanging from your neck.

Despite writing for a living, accurately describing the feeling of finishing a marathon is something I still struggle with. But one thing I can say, with confidence, is that it’s truly one of the best feelings in the world. I might be biased, but so too can the training be, the lead-up to race day, and the race itself, if you approach them with the right mindset (yes, even the bleak bits from mile 20 to 25).

Keen to know why you’d run a marathon? Always see the Instagram posts or hear stories of friends completing the distance, and just don’t get the appeal? You’re in the right place – especially if you’re Just Getting Started this New Year. If my love letter to the marathon distance below doesn’t encourage you to try a new sport – more specifically, running and the once-in-a-lifetime achievement of completing the 26.2-mile distance – then I don’t know what will. All it takes is a little curiosity, a touch of courage, and a willingness to see what you could achieve if you put your mind to it.

EAGER TO LEARN WHY YOU’D RUN A MARATHON? I’VE RUN TEN – MY GUIDE

My Initial “Why”

Let’s start with a bit of background for you. I’m Ally, a ten-time marathoner and three-time ultra-marathoner who, ten years ago, would probably have laughed in your face if you’d told her she’d complete four Boston qualifying marathons before the age of 30. I wasn’t not sporty as a kid – I did ballet to grade five, and netball, too – I’d just never been a runner, and so found the idea of 42.2 kilometres (!!!) hard to wrap my head around.

But when Cancer Research UK offered me a place at the 2018 London Marathon, I didn’t think twice. My grandma on my Mum’s side had suffered from breast cancer twice, so I wanted to run for her. Little did 22-year-old me know, but she’d sadly go on to die of lung cancer a few years later, and my Dad’s Mum would also go on to bravely fight pancreatic cancer, so it’d be a charity that remained close to home. Sadly, cancer affects most families, so I felt honoured to be able to do my bit and fundraise for a charity that did so much for mine.

My “why” at the time was emotional, as is the case for so many other runners. Motivated by pain, I wanted to give back – marathons are pretty unrivalled in that respect, and I challenge you not to shed a tear when you see some of the t-shirts runners don with pictures of their lost loved ones or the causes motivating them to achieve something they physically didn’t think they’d ever be able to do. Take the London Marathon last year, which saw approximately 56,640 runners complete the challenge and fundraise a world record amount of £87.3 million for charity, surpassing the previous year’s figures by £13.8 million.

Fast forward to 2019, and I was back on that start line – but with a slightly different “why.” This time around, I was there for me, eager to see if I could bank the elusive sub-four time so notorious in the running world. (Spoiler alert: I did).

For each of the eight other marathons I’ve completed, my why became slightly different. Some were simply to prove that I could; others, to see what my limits were during stressful or busy life periods. But one “why” remained the same – I run marathons because I know they make me a better person, each and every day.

Still on the fence? I’ve broken down a few more of my “whys,” below, in the hope they motivate you, too.

The Mental Shifts

One of the biggest reasons I’d encourage everyone and anyone to really consider running a marathon at least once in their lifetime? The undeniable mental boost running gives you, and the unrivalled ways it can alter your mindset for the better.

My early 20s were a sea of self-doubt, body image issues, and insecurity – but lacing up slowly but surely changed that, one run at a time.

Running – and the journey of training for and completing marathons, specifically – has made me calmer, more collected, more focused, and more driven. It’s proven time and time again that I’m capable of hard things, that I’m not a quitter, and that I can achieve (almost!) anything I put my mind to.

Interestingly, when researching for this article, I found out why – scientists believe that the “positive feedback loop” you create when you set a goal and achieve it can actually lead to long-term and lasting self-worth improvements, thanks to the chemical mood boost you experience when you accomplish something you set out to do. Giving yourself a goal of running a marathon and actually achieving it can – will – improve how you see and value yourself. So why not give it a go?

The Early Training Victories

I will never forget the feeling of finishing my first full week of marathon training. Three runs! While working a full-time job! And maintaining a social life! I was just so proud.

Achieving consistent small wins that aren’t solely linked to your work targets or personal life is a great way to expand your mood-boosting toolkit. Running will boost your endorphins anyway, but setting out to do something and then actually doing it boosts motivation, builds confidence and self-efficacy, fosters resilience, and reinforces both a positive mindset and habits.

As time’s gone on, my benchmarks have shifted slightly – as will yours, if you fall in love with the distance as much as I have and are keen to see where the joy of the running journey can take you. I now average five to six runs, two strength training sessions, and one yoga or Pilates a week. But that feeling of accomplishment, of having done something worth being proud of, still remains.

The Moments Of Doubt

There was a period in 2021 where I ran an ultramarathon, a 3:35 marathon, and then a 3:26 marathon – my first Boston Qualifying time! – in the space of about seven months. This was largely because we’d been locked down for over a year and so were a. unable to do much other than train and b. sorely missing mass events or races (I don’t condone overtraining, and must stress that proper R&R after each training block is absolutely essential for progress and overall health).

It was a magical few months for me, and an era that really sums up how much progress you can see in a few short months if you decide to commit to something and really give it your all. But I’d be lying if I said I wasn’t doubting myself non-stop. They were my first races off the back of investing in a coach, and my first really punchy time goals. My brain was constantly asking me – could I really do this? Was I cut out for such a challenge? Or was I being wildly optimistic with my goals?

But then I had a lightbulb moment. It was the same self-doubt that nearly stopped me from saying “yes” to my very first marathon, four years prior. And it also… really didn’t matter. I might meet my time goal. I might cross the finish line. I also… might not. And ultimately, all would be well in the world. We’d regroup. We’d go again. Running will always be there, and as a solo sport, you can be your own worst enemy at times. But perspective is key. As long as you’re proud of your efforts in training and put in the mental work, too, you’ll be in a solid place.

Think of it this way – if I’d let my inner critic win in 2018 prior to my first marathon, I’d never have found the sport or the self-confidence it’s given me.

Doubt, nerves, and uncertainty are healthy, in part – they’re a sign that you care, that you’ve given your all to a training block, and that your heart is in the right place. But reigning in wayward worrying is also a key part of the process. One of my favourite training and race day mantras is simple: “You can. And you will.”

The Highs

When you’re smashing your marathon training alongside a busy 9-5, you honestly feel invincible and like you can achieve anything. You have to be ruthlessly organised, willing to get up and out most mornings when it’s cold, and ready to loop your local park every weekend for hours at a time, but there’s an adulterated joy to it all which keeps millions across the globe coming back.

The highest high comes when you cross that finish line in a PB – for Valencia Marathon, which I ran in December, the time was one I’d only have dreamed of a few years ago. I ran a 3:13, averaging 4.35-minute kms, and that feeling of having done something you didn’t think possible is one of the best in the world.

I’ve never worked harder in a training block, banking near 80 km weeks, but my body responded well to the challenge, and my mind loved the stimulation, after so long away from the marathon distance (I broke my foot in December 2024, so I had to make the heartbreaking decision to DNS the London Marathon 2025).

The post-race beers tasted pretty special, too.

The Lows

Of course, what goes up must come down, and it’d be remiss of me to harp on about the many benefits of marathon training without also pointing out that yep – there will almost certainly be some lows. You’ll be tired. Your body will be fatigued as it becomes accustomed to your new workout routine and mileage. You’ll likely have to miss a few social events, and you’ll have to tweak your nutrition to make sure you’re fuelling adequately. You’ll be hungry, especially during peak weeks; you’ll get blisters, and likely experience chafing, and almost certainly go on some runs where you question your own sanity.

Getting up and out most mornings and banking 6+ miles in whatever conditions is never easy. And spoiler alert, we don’t always look forward to it, either. But if it were easy, everyone would do it. And it’s all worth it for that finish line feeling, and for knowing that you – yes, you! – did that.

BOTTOM LINE?

For anyone reading this article, I hope you’ve got a little glimpse into how transformative the marathon distance can be. It’s not just about the miles – it’s about the opportunity the challenge gives you, the blessing that fitness can be, and the things you learn about yourself, along the way. Long, lonely miles in the cold might not sound the most appealing, but they’ll give you quality time alone and force you to dig deep and prove that you can do hard things. You’re strong. You’re able. You’re alive.

And one final thing, before I go – don’t ever let anybody tell you that the marathon distance isn’t for you. Anyone can run a marathon. And I mean anyone, if you’re willing to commit, carve out the time for training, and do the hard work. I think this notion of “being a runner” can actually be quite detrimental and discourage people from giving a form of movement they might ultimately love a go. The only thing stopping you, is you.

If I’d listened to the naysayers all those years ago, I’d never have given marathons a go. But I’m grateful that I did, every single day. The determination, drive, and grit that the marathon distance takes has shaped who I am for the better – and it could you, too.