I tried running 5 km every day for a week (after 8 months off) but it all went wrong

Woman lacing up trainers/sneakers to go running on sunny day
(Image credit: Shutterstock / pio3)

This article is part of TechRadar's Get Fit For '25 series. All week long, we're publishing articles relating to fitness, health and the tech we're using to improve in 2025. You can view all the other articles in this series here.

Anyone I’ve met will know I’ve ran an ultra marathon, cycled 200 miles in a day, and finished the ToughGuy obstacle course twice. So, when given the opportunity to write about some fitness technology (and tell thousands more people about my achievements) I positively jumped at the chance.

Unfortunately, when I tell people about my sporting achievements, it tends to be received with mild confusion, as I no longer have the physique of an athlete. Since 2019, I've finished more pies and pints than kilometers ran. I got round the TCS London Marathon last year, but it was quite a few days until I could walk properly again. Time is a cruel mistress.

So, like many others in January, I am determined this time, more than ever, to 100% commit to (thinking about, maybe) getting really fit again. I’m also doing the TCS London Marathon again this year, and I’d like it to hurt a little less. Running five kilometers every day for a week – a theoretically simple challenge for a marathon runner – will kickstart my motivation to train in 2025 and cross that finish line in better shape, with a faster time.

Images of James Capell drinking a cocktail and finishing an ultra marathon

Me finishing an ultra in 2019 vs finishing a cocktail in 2024 (Image credit: Future)

Day 1: Everything is broken

James' first run stats

(Image credit: Future)

When I was asked if I would like to write something for TechRadar's Get Fit for '25 week, I was more interested in getting some extrinsic motivation to kickstart getting fit again rather than using one of the best running watches. I charged my ancient, no-longer-supported Series 1 Apple watch for the first time in five years but predictably, it didn't turn on. So, I dug out my slightly-less-ancient Wahoo Tickr (Wahoo also makes the Wahoo Kickr exercise bike and some of the best heart rate monitors), which dutifully lit up and synced to my phone.

Surprisingly my heart rate was listed as 190bpm with a 225bpm maximum, an almost impossibly high number. I used to track my heart rate to monitor my overall fitness and help me train in specific heart rate zones. Unfortunately, during the run it became clear that the heart rate monitor was no longer working.

An image showing the heart rate and elevation during James' run

My 5km time may be slow but there is 100m elevation on this route. (Image credit: Future)

If I do exercise, I usually use Strava, one of the best fitness apps, to track my routes for distance and time rather than my fitness. It's also a nice to reconnect with my old sporting pals. For this run, I used the map feature to find a nice five kilometer route near me and set off.

Within a few kilometers I am reminded why I love running. My endorphins are pumping and I'm holding back the urge to throw finger guns into the sky as I match my strides to my current favorite tunes. One kilometer later I am regretting letting myself get carried away, and I am dreading the last few hundred meters as they are like climbing a ladder. To make matters worse I accidently paused Strava and now need to run even more to make sure I hit my 5km.

After my first 5km, I don't feel too bad, but the initial excitement I had in the first few kilometers is replaced with doubt that my legs still have it in them to do this again for six more days, never mind the marathon.

Day two: I am having a medical emergency

An image showing the stats of James' second run

(Image credit: Future)

I have spent the morning trying to debug a web app on a VPS server and all I want to do is put my running shoes on and go for a run but I find myself having another thing to troubleshoot. I adjusted the strap of my heartrate monitor and it seemed to fix the issue of the elevated heartrate as it was syncing up with what I was counting.

Unfortunately before the 1km mark, I was having a medical emergency again.

An image showing the heart rate and elevation during James' second run

(Image credit: Future)

I had to fight myself out of the door for this run. I didn't sleep so well and if this was not a challenge, I would have happily knocked the run on the head and been satisfied that not getting enough sleep the day before is a good enough excuse to not run. Perseverance is the first lesson to learn in a challenge like this.

After I set off my ankle was complaining about something but I just ignored it. The first kilometers always seem to have some part of my body complaining about something and ignoring it seems to make it go away. If discomfort continues after a couple of kilometers or appears mid run I usually take it more seriously and stop and stretch.

Talking of stretching, I've not done any pre- or post-run mobility work. I've never really been a stretcher but I know it's something I need to incorporate when I start putting in more runs a week during my marathon training.

Two kilometers into my run I was making pistol fingers and poking the air while mouthing lyrics again. I was even looking forward to the hill at the end. Since I didn't pause Strava half way through this time I feel like putting the effort down and getting a good time.

I beat all my records from the previous day and my legs didn't feel that battered but I can feel a blister developing and after my heart rate settled down I felt more unfit than ever and less excited about the prospect of running regularly.

Day 3: avoiding the ladder

An image showing the stats of James' third run

(Image credit: Future)

Despite waking up with a cold I was quite eager to do a run, which is a nice change. My legs didn't have any aches or stiffness in them and I was looking forward to the rush. One of the best things about being unfit is that the "runner's high" comes quite quickly. One thing I was not looking forward to is the last few hundred meters.

So, I get on Strava and map out a 1km route with less elevation. It's right next to my house and I know there is a decent, but I seem to remember that it's only a moderate climb back up to the main road and down again. This should be easy!

It was not. I had to dig deep to convince myself to keep going: the previous route despite having more total elevation, spread out the climbs a bit better giving my legs time to recover during the flat portions of the run.

The elevation on James' third run.

(Image credit: Future)

On the second lap I was trying to reason with myself. Repeating over and over that the next lap I would be over half way and then there is only one more lap before the last lap. Instead of avoiding a ladder I've essentially given myself five to run up and down.

I remember I felt pretty bad in the last 20 km of my ultra. I got through by telling myself that I could do one more stride over and over again and only allowed myself to be concerned about the current kilometer. It doesn't feel great being so far away from my former self, but everyone has to start somewhere and there is no shame in that (another key lesson from this challenge). There is also no shame in having to start again.

I gave up on my last lap. I could not face doing it again, and instead of looping back around,I decided to run further up the hill which (although it was more climbing) it was less steep and I could manage a gentle downhill jog to the finish.

On the upside, I now have a reference point. I don't have any heart rate data but I know that if I can easily do the last 1 km loop on this route next time then I'll have made progress.

Day 4: the first challenge

An image showing the stats of James' fourth run

(Image credit: Future)

My cold is worse now and it is raining. I don't even want to stand up from my desk to make a coffee. Going for a 5km run is not an attractive proposition. Apart from my cold, I don't have any aches and pains in my legs.

Today's mission is to just get the run done. I'm going to run 2.5 KM away from my house on the flattest possible path, and then turn around and get back. No heroics, no PBs, no getting carried away with myself after the first couple of kilometers and then regretting it in the last two.

Yellow wind warning

(Image credit: Future)

So, I step out of the door and I am instantly met with sideways rain in the face. I wrapped up warm with gloves, fleece-lined tracksuit pants, and a waterproof jacket. All mistakes.

The pants are instantly wet through and are now not only cold against my skin but also heavy and rubbing against my legs. My waterproof jacket's sole purpose seems to be to collect water from my upper body and deposit it onto my lower body. Next lesson: shorts, perhaps with tights underneath, even in cold and wet weather. I actually knew this, I just forgot.

"Just get the run" done I say to myself, slowly putting one foot in front of the other. Sure enough, after 40 minutes I'm back home and out of my wet clothes. I don't feel particularly triumphant, but I'm happy that I've not failed my challenge just yet. Hopefully my sickness will be better tomorrow and I can put a better effort down.

After four days there definitely seems to be a change. Despite my cold, I am actually starting to look forward to my runs. Consistency in action!

Day 5: a new toy

James' 5th run

All subsequent runs are automatically synced to Strava (Image credit: Future)

I'm trying to not make this an article about me having a cold but it is currently a significant burden to this challenge. I'm not sick enough to call in sick for work, but sick enough to have poor sleep quality and comfort which is having a big impact on my energy and focus. It's making this challenge a lot more difficult than I anticipated it to be. At least I have broken the back of the challenge and (after this run) there are only two more runs left.

In the face of the challenges, I'm excited for this run because I have a new toy and I seem to be more excited about running in general. After telling our Senior Fitness and Wearables Editor Matt Evans that my watch and heart rate monitor have kicked the bucket, he said that he would send something to me. I'm not sure what I was expecting but it was certainly not the Polar Vantage V3.

James wearing a Polar Vantage V3

(Image credit: Future)

I wasn't into sports watches. I always thought that low battery life common among the best smartwatches made them redundant as a watch and fitness tracker, but after I read the stats I was pleasantly surprised and eager to try it out.

This run was very much like the previous two. Not fast, just trying to finish.

Day 6: the penultimate run

I am looking forward to getting this over and done with. After the first few runs I started to actually get excited about running, and maybe even doing some interval sprints. However, getting a cold changed my focus to just trying to complete it rather than trying a wider variety of training runs.

The Polar Vantage V3 has a feature (common amongst the best running watches) that warns me when I stray out of a heart rate zone. I planned to set it to zone three and run to that, rather than run to how I feel. My usual way of running is to run as fast as I feel comfortable and if I go a bit too hard, back off a bit and recover.

When I went for a longer run of course, I would be a bit more careful and not let my heart rate get too high at all. As I've been out of the game for so long I seem to have lost this ability and although I start off quite slow, it's not slow enough and I am struggling in the last few kilometers.

I couldn't bring myself to finish this run. My cold has got the better of me. I do the right thing and call in sick for work, make myself some chicken soup, and rest and recover. I thought about changing the title to 'Can I run 5 km every day for 5 days?' but that's cheating.

Day 7: thinking positive

So, I may not have managed to complete my challenge of running 5 km every day for seven days but I also had a secondary goal to jumpstart my 2025 fitness journey. I consider that goal well and truly achieved.

Part of taking these last two days off is because I'm excited about putting down some decent runs again. Just running for the sake of completing a run when I have a cold is not productive. Putting down a longer run at a lower intensity or a shorter run at a higher intensity is, and the sooner I recover the sooner I can do that.

Last week I was not that motivated to run or to get fit at all. It felt like something I should do, not really something I wanted to do or something that I would enjoy. I am now properly looking forward to my next run and I am eager to use my new watch to help me get a good base level and then build on that.

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James Capell
B2B Editor, Web Hosting

James is a tech journalist covering interconnectivity and digital infrastructure as the web hosting editor at TechRadar Pro. James stays up to date with the latest web and internet trends by attending data center summits, WordPress conferences, and mingling with software and web developers. At TechRadar Pro, James is responsible for ensuring web hosting pages are as relevant and as helpful to readers as possible and is also looking for the best deals and coupon codes for web hosting.