The challenge was simple: run 5k every day for 28 days. No rest days, no shortcuts, no doubling up to get ahead. Just 5k, every day, regardless of how I felt.

I wasn’t starting from scratch, but I wasn’t in peak running shape either. My training had been half-hearted for a while – enough to get by, but not really enough to improve. I knew 5k was doable on any given day. The question was what it would feel like doing it 28 times in a row, with a sleep-shy toddler, work and general life distractions thrown in. I also kept strength training twice a week throughout – mainly because I didn’t want my gym numbers to completely fall off a cliff.

The plan – if you can call it that – was to hold everything steady and see what gave first.

5K a Day

The first week felt like a chore more often than not. A couple of runs came straight after the post-work commute, when motivation was low and the run itself didn’t do much to improve things. One evening in the rain was particularly grim. Another came off the back of no sleep, was left until late and done purely because it had to be.

The gym treadmill made an appearance one lunch break, which was an immediate mistake. Five kilometres indoors felt far longer than it should, even when breaking it up with intervals just to stay engaged.

By the second week, fatigue started to build. Day nine stood out as the hardest – low energy, heavy legs and no real explanation beyond the fact that everything was adding up. It didn’t feel like I was getting fitter, just more tired.

Around the middle of the challenge, things became more manageable. The daily effort started to feel less like a battle and more like routine. By day 20, it was just part of the day.

Daily Habits

Our fitness director, Andrew Tracey, explains the rationale behind daily fitness challenges.

‘If you’re looking to make a habit really stick, to the point where it’s almost automatic, then daily adherence can remove a lot of decision fatigue and deliberation. A study in the European Journal of Social Psychology found that, on average, it takes 66 days to achieve automaticity with a habit, but that daily adherence accelerated this time greatly.

‘That being said, “daily workout challenges” tend to be found at the extremes: Facebook mums committing to 30 squats a day for a month (no shade, a great thing to do), or YouTube men documenting their weird new obsession (“You won’t believe what happened when I did this for 30 days…”). They also tend to veer from harmless, and usually fruitless, to ill-advised and self-destructive. But there’s a lot of evidence in favour of building daily habits – especially fitness ones – and the benefits these can have on the rest of your life.’

Progressive Overload

I wasn’t new to running, but if you are, heed this advice from Daine McKibben Rice, director of Validus Sports Injury Clinic.

‘Running 5k every day for 28 days is less about distance and more about load tolerance. For most people, 5k daily represents a pretty significant increase in cumulative load, particularly if they’re not already running regularly. The strongest evidence shows that rapid increases in training load are the primary driver of running-related injury, rather than distance alone.

‘For beginners, the risks are higher. Around one-third of recreational runners sustain injuries annually, with overuse injuries being the top of the list: such as tendinopathy, shin splints or patellofemoral pain. This can be due to repeated loading without sufficient conditioning or recovery, as musculoskeletal tissues take more time to adapt compared with cardiovascular fitness.

‘A gradual build-up is essential. For beginners, increasing running volume by 5% per week and progressing from two to three runs weekly towards consecutive running days is a safer approach than starting with daily 5k runs.’

It wasn’t all sunshine and rainbows…

By the final day, I wasn’t desperate for it to end, which felt like an achievement in itself. I finished with a 5k time trial and came within 30 seconds of the 20-minute mark – not an all-time PB, but the quickest of the year and better than expected given there hadn’t been a single rest day in four weeks.

The more interesting result was how quickly my body adjusted to running every day. Individual runs didn’t suddenly feel easy, but they stopped feeling like a big deal. It became normal to head out, get 5k done and move on.

The strength training was where things got confusing. I expected my numbers to dip, or at least stall, but the opposite happened. At the end of the challenge, I hit a two-rep squat PB. Which either says something about the benefits of consistent training or suggests I’d been underperforming before. Possibly both.

In body composition, not much changed. I didn’t lose muscle, but I didn’t drop any body fat either. That’s probably down to eating more to keep up with the extra running. Daily cardio on its own isn’t a guaranteed shortcut to getting leaner, especially if you’re fuelling properly. And to be fair, that wasn’t the point of the challenge anyway.

Running every day isn’t something I’d recommend in the long term and it’s not the smartest way to improve performance. But as a short, controlled block of consistency, it does exactly what you’d expect: it builds a habit, raises your baseline and proves you can handle more than you think.

Isaac Williams is Site Editor for both Women’s Health UK and Men’s Health UK, guiding and supporting the content teams to create content across all platforms. Isaac’s love of health and fitness began at Loughborough University, where he graduated with a History and English degree in 2014. His first job was at Men’s Running magazine, where he progressed from Staff Writer to Editor. Among his highlights of those four years include completing a 24-hour track race (never again), just about finishing a multi-day ultramarathon in the Azores, and chugging his way around a ‘beer mile’. Isaac ventured into the world of freelance journalism in 2018, interviewing some of the biggest names in sport – like Anthony Joshua and Ben Stokes – and writing features for the likes of The Guardian, Red Bull, ShortList and BBC Countryfile. He was also a regular contributor to an adventure series called ‘The Man Who’: speaking to some of the world’s most extreme explorers from the wilds of Caffè Nero. In late-2019, Isaac became Editor of Men’s Fitness UK. In his five years there, Isaac was responsible for editing the monthly magazine and managing website content, ultimately helping the brand transition to a ‘digital-first’ approach. He joined Hearst UK as Multiplatform Editor in December 2024, where he manages day-to-day digital output, edits content and writes articles on all things health and fitness. When he’s not hammering at his keyboard, Isaac enjoys exercise and trying –  unsuccessfully, so far – to teach his baby son to kick a football. You can follow Isaac on Instagram @isaacw1993. 

Known for her disciplined approach to fitness, Jennifer Aniston has been using the Pvolve method for five years to build strength and mobility. Her trainer, Dani Coleman, recently shared the biggest changes she’s seen in Jennifer’s fitness since they started working together.

‘She has always been passionate about movement and wellness. But it has truly been game-changing to watch her strength year after year just get better and better, and to see her mentality shift with how she imagines what a successful workout is,’ she said on an episode of The Bossticks podcast.

Jennifer used to define a successful workout as one that was more traditionally intense. But she’s realised that ‘you don’t have to break your body down to get a good workout’, Dani revealed.

‘She’s talked about previous injuries she’s had and how she used to think that you needed gruelling workouts, even when she had a back injury. I think the most rewarding thing is really seeing her mindset shift.’

It’s therefore been especially gratifying ‘seeing Jennifer level up her weights and just trust me to put her through it now’.

Jennifer agrees.

‘Simpler is better – and consistency,’ she said in a recent Pvolve clip.

Pvolve founder Rachel Katzman also acknowledged that Jennifer now believes the best workouts build up and support her body, rather than punish it.

‘The one thing she always says is, “I wish I had this in my 20s,”’ Rachel said of Jennifer’s enthusiasm for Pvolve on another recent episode of The Bossticks.

‘“I wish I didn’t destroy my body when I was younger to look a certain way because that’s what I thought I had to do,”’ she continued. ‘And now with Pvolve, I look better than I did back then. I feel better. I’m stronger. I’m leaner. I just have more energy.’

Jennifer Anniston’s current Pvolve routine

Rachel confirmed key details about Jennifer’s workout schedule.

‘I heard a little rumour that she does Pvolve only four days a week,’ podcast host Lauryn said.

‘I think that rumour’s true,’ Rachel confirmed.

‘And she does an hour,’ continued Lauryn.

‘You can ask Dani for specifics, but yes,’ Rachel replied.

The founder also emphasised the importance of strength training and described her own changing attitude towards lifting weights.

‘I’m definitely going up in my weights. I was somebody who was very, very scared of weights. I didn’t even want to use a 2lb (0.9kg) weight. Now, I’ve got my 12lb (5.4kg) and my 15lb (6.8kg) weights.’

Echoing her, Dani’s main piece of advice for Jennifer – and trainees more generally – is still ‘to prioritise strength, as well as your mobility and stability’.

One of our most frequently asked questions here at Women’s Health? How to build muscle and burn fat at the same time. So, we asked superstar trainer Oyinda Okunowo exactly how to do it. In this 4-week plan – created exclusively for Women’s Health COLLECTIVE members – you’ll get the workouts and nutrition guidance needed to help you on your way to better body composition. Tap the link below to unlock 14 days of free access to Oyinda’s plan and start training today.

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