Gareth Fletcher, a web editor who lives in London, decided to try a new way to stay fit outdoors with British Military Fitness.
Gareth is a keen runner who enjoys long distance running. But while he already had a good level of fitness, he was keen to find a different way to stay fit.
"I was bored of doing the same exercises every time I went to the gym," says Gareth. "And although I love running, when I don't have an event to train for I find it hard to stay motivated.
"I was looking for a new activity away from the gym, when I saw an advert on the Tube for British Military Fitness."
The sessions take place in parks all over the UK and are run by serving or former members of the armed forces.
My first foray
The British Military Fitness website has videos of a typical session, so Gareth already had a good idea of what to expect when he turned up for the free introductory session on Clapham Common in southwest London.
"I was surprised by how popular it was, but also that most of the participants were women," says Gareth. "I'd imagined military fitness was a very male thing, but I was wrong.
"Each session lasts an hour, including a warm-up and stretching at the end. There are three levels – beginner, intermediate and advanced – and I tried the beginners' class to start with.
"The session was intense. It involved a lot of running, both jogging and some sprinting, and the kind of exercises I used to do in PE lessons at school: press-ups, sit-ups, squats, jumping jacks, and an exercise called a burpee, which everyone seemed to hate. The exercises were all very simple and the instructors demonstrated everything first.
"There were lots of team exercises and partner work, too, which could be anything from relay races to arm wrestling. You keep switching partners throughout, so you get to meet lots of different people.
"By the end of the first session, I was sweating a lot and felt like I'd had a good workout. I really enjoyed it, but I didn't feel worn out. So the next time I tried the intermediate class.
"This was much harder and more intense still, and the fact that everyone else in the group was fitter made me work harder as I didn't want to be left behind.
"The exercises were similar to the beginners' class, but there was less time to recover between them and we did them in longer bursts."
"Having an instructor there is really motivational, and everyone in the group is encouraged to cheer each other on.
"Although it's based on military training techniques, the instructors aren't too harsh or strict, and the atmosphere is very lighthearted.
"Overall, you get a really good cardiovascular workout, plus by doing press-ups, sit-ups and squats, for example, you're working different parts of your body, such as your legs, chest and stomach muscles.
"The instructors work on a rota, so you end up doing something different each time, which keeps it varied and stops you getting bored.
"My local classes take place in the morning and evening after work, and on weekends, too, so I find it easy to fit into my day. You have to pay a monthly subscription, but it works out cheaper than most gyms.
"I really enjoy exercising outdoors instead of in a hot, stuffy gym. However, so far I've only done it in good weather, and I think it'll take a lot more motivation to go when it's cold or raining.
"While there are beginners' classes, they're still hard work, so I think you might struggle if you'd never exercised before, although the organisers say they're suitable for people who are just starting out.
"It's recommended that you see your GP if you have any concerns about your health before you come to a session. One of the sessions I went to involved carrying people on your back, which might not be suitable for everyone.
"For me, exercise is about enjoyment and having fun, as well as keeping fit and looking and feeling good, and British Military Fitness ticks all the boxes."
British Military Fitness sessions involve high-impact exercises and activities that may not be suitable for everyone.
If you currently do little or no exercise, it's a good idea to gradually increase your everyday activity levels before trying these classes.
The Live Well Fitness section has lots of ideas for incorporating activity into your daily routine.
If you feel out of shape, are recovering from injury, or are worried about an existing condition, see your GP before you start any new fitness regime.