My team of around 15 people, from ages 10 to 60, run down a bank and straight towards a big muddy stream.

“Are your trainers on tightly?!” yells the leader of the group. “If they’re not, you’re about to lose your shoes and the zombies are on their way!”

We run straight into the water and quickly realise what he means, instead of reaching the bottom, we’re being sucked into a muddy quicksand bog. My shoes are stuck, as is three quarters of my left leg and I can feel one trainer slipping off its heel, while the mud seeps inside. From the groans around me, I guess that everyone else is in the same boat.

I reach for the bank and pull my legs out, wading to the other side. As we all eventually reach dry land, we hear a different type of groan behind us and see a six foot man with a skeleton head, running over a hill in our direction – We’re off again.

Back at the race, we’ve broken off from the team and I’m running through what we think might be a short cut in the trees,along with five others.   Around our waists are belts with coloured tags attached, it’s these tags that the zombies are after, if you have no tags you’re dead.

Looking around, we’re all holding up pretty well, with most of us only missing one tag. In zombie outbreak terms we’ve probably got a bandaged wound, but nothing life threatening. One boy however, is on the last tag – at least a zombie bite – and with most of the trail still ahead of us its not looking good. He knows it and stays in the middle of the pack.

Coming out of the trees we all suddenly see the mistake we’ve made, instead of cutting out some of the trail, we’ve run straight towards three small zombie girls in slashed up dresses, with a large bog and a steep muddy hill in the way of our only escape route.

As we run into the muddy water, I notice that the long bog is actually broken up by four wooden beans, just underneath the water.  Someone appears at the side of the bank and shouts to us. “Rules of this crossing are that you can’t go over, the only way across is to go under the wooden beams….”

That’s just what we’ll have to do then.

No one hopes to feel scared in everyday life. Fear is a sign of danger, distress and things going wrong, but yet it’s a sensation we search out constantly.

There’s good fear and bad fear. Bad fear is usually connected to stress, it’s the knot in your stomach that makes you less productive and want to stay at home instead of going out to meet your friends. Good fear on the other hand gets you going, it makes your heart beat faster and your senses more alert – it’s the feeling you get just before that big drop on a rollercoaster, that’s the fear we’re addicted to and the fear that we like to feel in our exercise routines.

“Being scared gets us pumped up,” says psychotherapist Charlotte from Good:Mind counselling.

“Fear creates high levels of physiological arousal. Our blood pressure increases along with our heart rate and the hormone adrenaline is released leaving us highly charged and ready for action.”

When we’re scared, as well as making us physically more ready to act, our brain tells us to focus on the object of our fear and finding a way to escape it. This makes it an amazing way to lose all self consciousness about working out and make it not feel like so much of a strain. In a matter of words, we’re using horror monsters as super effective motivation coaches.

“These are two different types of fear however, the pleasure we get from horror comes from the relief that follows, offering a powerful emotional release from the mundane every day yet knowing that we are safe,” says Charlotte.

“The great thing about horror is that it’s a good way to confront a scary experience in a safe context which prompts production of the feel good hormones serotonin and dopamine.”

Fear can also bring out the best in us, it seems. As a group of strangers, with zombies on our tails, we’re helping each other out at each step of the way. The more immersed we become, the more of a team we felt. We don’t just look after ourselves, we look after the clan. It’s an instinct that quickly takes over.

Over an hour after the first whistle blew, the finish line and safety from the outbreak comes into view. Five zombies and a series of haystacks are all that separate our gang of survivors to the end point, and we all have one remaining tag each.

We all leg it. Running through the zombies side by side, I see the woman beside me miss a jump on the haystack and get caught by a creepy little undead girl to her left, the guy to my right narrowly misses having his tag stolen by another. Five of us make it to the finish line together, and it’s all over.

Running over to the spectators, I feel pumped. I’d been doing some hardcore physical activity for the past 60 minutes, but my body doesn’t feel tired at all. I wonder if it wasn’t as strenuous as it seems after all.

Two hours later on the train to London however, my arms and legs are in some serious pain. All the pulling myself over walls and running through mud had taken effect.

Two days later, and I’m even more sore, convinced that horror-themed workouts are the most effective way in the world to really get your body work to its limits. I’m a total zombie run convert.

It seems that if you’re looking for a way to get into fitness, the answer is to get spooky.