Military-ready fitness requires more than simply being strong or having a big aerobic engine. You need to be able to cover ground for long periods, produce force when you're fatigued and still have another gear when the intensity ramps up.
According to YouTuber Harry Shepherd, who draws on his experience of Royal Marines-style fitness, that means building your training around three key areas: aerobic endurance, lower-body strength and high-intensity conditioning.
'This is the three-step process to never gas out and have unbreakable endurance when it comes to military fitness,' Shepherd says. 'It's exactly how you can build your engine and build your endurance in a way that carries over to being specifically military fit.'
You don't need to be preparing for military selection to benefit, either. The same combination can help build the kind of well-rounded fitness that carries over to running, hiking, hybrid training and plenty else besides.
3 Steps to Building Military-Ready Fitness
1. Build Your Aerobic Base with Zone 2
Military fitness requires the ability to spend long periods on your feet and keep moving even when fatigue starts to build. That's where a strong aerobic base comes in.
Shepherd puts zone 2 at the bottom of his fitness pyramid.
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'We need a good amount of zone 2 work, where we're staying in that aerobic base-building area for a period of time,' Shepherd says. 'Zone 2 is essentially your long, boring, easy miles, and we're going to look at spending 80% of our cardio work in that area.'
Think running, cycling, rowing or using the stair climber at an easy, sustainable intensity. Shepherd suggests working at around 60-70% of your maximum heart rate, although heart-rate zones vary between individuals and devices.
A simpler gauge is the talk test: the effort should feel controlled enough that you can maintain a conversation without gasping for breath.
The aim isn't to leave yourself sprawled on the floor. It's to accumulate plenty of aerobic work you can recover from and repeat consistently.
2. Build Serious Lower-Body Strength
Next comes lower-body strength.
That's hardly surprising. Whether you're running, carrying kit, climbing or simply spending hours on your feet, stronger legs give you more physical capacity to work with.
Shepherd recommends training the lower body twice per week, ensuring you're strengthening the quads, hamstrings, glutes and calves.
His approach is to build each session around what he calls a key performance indicator (KPI) lift – a movement such as a deadlift, back squat or hip thrust that you can track and progressively improve.
'The KPI method is super simple. We're going to have a key movement, and then we're going to build the session off that,' he says.
'If our lower body session starts with a deadlift, for example, we're going to use that as our strength metric. And then from there, we might do some hip thrusts. We might do some RDLs. We might do some hamstring curls. That's how we're going to think about our lower-body strength.'
The benefit is simplicity: rather than trying to improve everything simultaneously, you've got one big lift providing an objective measure of whether you're getting stronger, with accessory work filling the gaps around it.
3. Add VO2-Max and Power Work
Once you've built the base of the pyramid, Shepherd adds the sharper stuff: VO2-max training and explosive work.
'We need the sharper end of the spectrum where we're looking at VO2 max and power,' he explains.
For cardiovascular work, that means hard intervals such as 400m, 600m or 1km efforts, interspersed with enough recovery to maintain the quality of each rep. Rather than obsessing over hitting an exact heart-rate percentage – which can lag behind your actual effort during shorter intervals – aim for hard but repeatable efforts that have you working close to your upper aerobic limit.
Power training has a different goal: producing force quickly.
'Power is basically speed plus load,' Shepherd says. 'With our power, we want to make sure that our intensity is really high, load is pretty high, and volume is low.'
That could mean explosive jumps, throws or fast, low-rep resistance exercises. The important part is maintaining speed and quality rather than grinding through increasingly slow reps under maximal loads.
Put all three layers together and you have a straightforward template: build enough aerobic fitness to keep going, enough strength to make physical tasks easier and enough high-end capacity to turn up the intensity when required.
You might not need to be Royal Marines-ready. But being harder to tire, stronger and more explosive isn't a bad consolation prize.
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Ryan is a Senior Writer at Men’s Health UK with a passion for storytelling, health and fitness. Having graduated from Cardiff University in 2020, and later obtaining his NCTJ qualification, Ryan started his career as a Trainee News Writer for sports titles Golf Monthly, Cycling Weekly and Rugby World before progressing to Staff Writer and subsequently Senior Writer with football magazine FourFourTwo.
During his two-and-a-half years there he wrote news stories for the website and features for the magazine, while he also interviewed names such as Les Ferdinand, Ally McCoist, Jamie Redknapp and Antonio Rudiger, among many others. His standout memory, though, came when getting the opportunity to speak to then-Plymouth Argyle manager Steven Schumacher as the club won League One in 2023.
Having grown up a keen footballer and playing for his boyhood side until the age of 16, Ryan got the opportunity to represent Northern Ireland national futsal team eight times, scoring three goals against England, Scotland and Gibraltar. Now past his peak, Ryan prefers to mix weightlifting with running – he achieved a marathon PB of 3:31:49 at Manchester in April 2025, but credits the heat for failing to get below the coveted 3:30 mark…
You can follow Ryan on Instagram @ryan.dabbs or on X @ryandabbs_
