I’m training to run a half marathon in October.

Way back in January, I was mindlessly scrolling through social media when an advert for the Royal Parks Half Marathon popped up – an invitation to enter the ballot for a place. “Why not?” I thought. It would give me an excellent focus to improve my fitness, which had taken a severe bashing thanks to a relapse of Graves’ disease a few months before. Not only was I unfit, I was also overweight. And the race was being held on the 12-month anniversary of my relapse.

I completed the ballot entry, resisting the urge to pay a fee to increase my chances by going into a second draw. I’ve been caught out by that many times in the London Marathon ballot. A week later, I received an email telling me I had a place. At the time, I didn’t think I’d been particularly lucky, but I’ve since learned that demand is huge, and many people are unsuccessful.

My running history has been sporadic.

My false start

In 2013, I signed up for a 10k to celebrate the one-year anniversary of the London Olympic Games, with the finish line inside the Olympic Stadium. I started the Couch to 5k programme. It didn’t go well. At first, I thought my sports bra was too tight, but I had to admit that something more serious was behind my chest pain. A GP appointment and ECG revealed nothing, but I still cancelled my place. I persevered. If I ran slowly enough, I could keep the chest pain and lightheadedness at bay. It seems ridiculous now, but I never imagined anything was seriously wrong. My (incompetent) GP agreed.

In 2015, I signed up for the same 10k again. I completed it, but had to walk most of the way as any attempt to run left me so lightheaded I nearly passed out.

The diagnosis that changed everything

I decided to take matters into my own hands, booking a private cardiac examination. A few days later, I was diagnosed with severe aortic valve stenosis and told not to exercise until I had open heart surgery to replace the valve. That surgery happened just seven weeks later.

A few weeks after the operation, I started running again. It felt incredible to run without chest pain, breathlessness, or dizziness. I began doing Parkrun and eventually brought my 5k time down to just over 32 minutes.

Just under a year after my heart surgery, my best friend died of bowel cancer. I signed up for the Southampton Half Marathon, which took place on what would have been her 58th birthday.

Training for a half marathon is not for the faint-hearted. You have to run three to four times per week, with one of those runs gradually increasing in mileage. I made it to 9 miles the week before the race and completed the event in 2 hours 45 minutes. Slow but I got it done, raising over £1,000 for Bowel Cancer Research.

A few months later, I completed the Richmond Park 10-mile event. Since then, I’ve done a handful of 10ks, earned my 100th Parkrun vest, and run 8k in each of the Hyrox events I’ve entered.

Training for a half marathon

For a few weeks, after I got my ballot place, I didn’t do much. But as time went on, I knew I had to make a plan and get the work in. So I turned to ChatGPT, something that didn’t exist back in 2016. I put in my details (age, current exercise routine etc.) and asked for a 12-week half marathon training plan. With my knowledge of training, as a participant and with my personal trainer qualifications, I could see it was as good as any I’d found before. I started the plan 13 weeks out, to account for a week of hiking in September when I wouldn’t be able to run.

When I got my place in the Royal Parks Half Marathon, I had just over 8 months to train. I was unfit, with a VO₂ max (according to my Apple Watch) of 27.6.

And it’s going well. My VO₂ max is now 33 – the highest it’s been since early 2020, when I was probably at my fitness peak post hitting the big 60.

The feeling of being fit is incredible. It’s not just a number on a phone. Life simply becomes easier and more enjoyable. If it could be bottled, it would be priceless.

But training never really gets easier. You just go faster and longer. That’s how the gains are made.

I’m still slow, and I expect my 2025 half marathon time will be similar to my 2017 one. But I will cross that finish line. And I’ll get my medal.