Stable Energy Requires Movement

en·er·gy | noun | the capacity to do work.

Great. Very helpful. Somewhere between “the capacity to do work” and “why do I want to lie face-down on the office carpet by 3pm,” something got lost in translation.

Here’s a scenario you might recognise. You wake up tired. You tell yourself you’ll go for a walk at lunch, or maybe hit the gym after work, once you have some energy back. So in the meantime you sit: in the car, at your desk, in back-to-back meetings, at lunch (delivered, obviously, because who has time), carefully conserving whatever energy you’ve got left for later. For the version of you that has energy.

That version never quite shows up. By 4pm you’re half-googling “why am I always so tired” between meetings, and you already suspect the answer isn’t going to be “nothing, you’re fine.”

Here’s the twist nobody tells you: the sit-still-to-save-energy plan is backwards. To understand why, you need to meet the guy actually in charge of your energy supply. He’s not you. He doesn’t care what you think. And he is, frankly, a little bit of a jerk about it.

Meet the Power Plant Manager

Inside almost every cell in your body live these tiny structures called mitochondria (yes, the “powerhouse of the cell” thing you half-remember from school, right before you forgot it forever to make room for song lyrics).

Here’s what they actually do: they take the food you eat and the oxygen you breathe and turn it into ATP, which is the actual currency your body spends on everything: your heartbeat, your muscles, your ability to sit through a two-hour meeting about the meeting you had yesterday without face-planting onto the table.

Now picture all of your mitochondria, collectively, as one guy. Let’s call him the Power Plant Manager. He runs the energy grid for your entire body, and he operates on exactly one principle:

Don’t maintain capacity nobody is using.

He is, in short, a deeply unsentimental facilities manager. He walks the floor of your body with a clipboard, and if a piece of equipment hasn’t been used in a while, he doesn’t get sentimental about it. He shuts it down. Sells the parts. Moves on.

Your heart gets the five-star treatment: round-the-clock staffing, because it beats around 100,000 times a day and does not, ever, take a day off. Heart cells are absolutely stuffed with mitochondria, practically wall-to-wall power plants, because the Manager has never once seen your heart slack off. Your muscles, on the other hand, get whatever they can justify. Use them a lot, and he keeps investing. Barely use them, and he starts quietly decommissioning the plant.

Why He’s Currently Downsizing Your Department

Here’s where it gets personal. When you move (walk, climb stairs, take the long way round purely out of spite for the lift), your muscles send a memo up the chain: we needed more energy than usual to do that, please staff accordingly.

The Manager reads that memo and does what any reasonable manager does: he builds more capacity. This is a real, well-documented biological process called mitochondrial biogenesis, and regular movement is one of the most reliable ways to switch it on (Perry & Hawley, 2018). Translation: move regularly, and your body assumes you’ll keep doing that, and quietly upgrades the plant to keep up.

Stop sending the memo, though, and he assumes the opposite. No demand, no investment. This isn’t just a dramatic metaphor: put someone on total bed rest for even a few days, and you can measure the metabolic machinery inside their muscles shrinking (Dirks et al., 2012). The Manager doesn’t wait for a strategy review. He starts cutting almost immediately.

So when you feel tired and decide the responsible move is to sit very still and conserve your energy, from his desk, that doesn’t look like rest. It looks like a permanent drop in demand. And he adjusts your capacity accordingly. Downward.

The Low-Energy Loop

This is where a lot of professionals get stuck, and it goes like this. You feel tired, so you move less. You move less, so the Manager cuts capacity. With less capacity, everything physical feels harder: the stairs feel steeper, the walk feels like a chore, the gym feels borderline hostile. So you move even less. Which gives him even more reason to cut further.

Nobody designs this on purpose. It just quietly happens, one skipped walk and one extra lift ride at a time, until six months later you’re winded by a flight of stairs and blaming it on “getting older,” which, plot twist, might have less to do with your age and more to do with how long you’ve been in the Loop.

Most people try to escape it from the wrong end. Another coffee. Something sweet at 4pm. An energy drink with a name that sounds like a fighter jet. A supplement promising to “recharge your cellular energy,” as though your body were a phone you left in a drawer. None of these send the Manager the memo he’s actually waiting for. They just paper over the shortage for an hour or two.

There’s a second trap hiding in here too: sitting still doesn’t automatically count as recovery, even when it feels like it. After a brutal morning of meetings, collapsing into your chair can feel like relief, and sometimes it genuinely is. But physiologically, sitting is mostly just the absence of movement. It doesn’t mean your nervous system is recovering, and it definitely doesn’t impress the Manager. We’ve built entire working days almost completely out of sitting: sitting on the commute, sitting at the desk, sitting in the meeting, lunch delivered so nobody even has to stand up for that, and then try to undo ten hours of near-total stillness with one furious hour at the gym, as if that hour is going to overturn his decision.

Your Brain Is on the Same Budget

Here’s the part that should really get a leader’s attention: your brain isn’t exempt from any of this. Thinking, focusing, keeping your temper in a tense meeting, switching between eleven browser tabs of context: all of it runs on the exact same energy system the Manager oversees.

To be clear, ten squats before a board meeting will not summon a sharper decision out of thin air. Physiology doesn’t work like a vending machine. But the biological capacity behind performance can’t be fully separated from how much you actually move your body. Plenty of us spend entire days almost completely motionless while demanding peak cognitive output from ourselves (sustained focus, hard conversations, fast decisions, constant switching) from a system whose physical side got zero stimulation all day. That mismatch deserves more attention than most performance conversations give it.

What Happens After 40

This all gets more urgent as you get older, because mitochondrial function and aerobic capacity both tend to decline with age (Distefano et al., 2014), and muscle gets harder to hold onto no matter what you do. It’s tempting to file the resulting fatigue under “that’s just 40 for you” and move on.

Except age and inactivity have a nasty habit of arriving together. You get busier. Your role gets more sedentary. Travel eats your training time. Life outbids the gym for your evenings. The movement that used to happen automatically at 25 quietly evaporates, and by the time you notice, it’s easy to blame the calendar instead of the actual culprit: a decade spent in the Loop.

Here’s the genuinely good news: the Manager doesn’t retire. He keeps responding to demand at almost any age. A recent meta-analysis of exercise studies found real, measurable gains in mitochondrial capacity even in older adults who started training later in life (Abrego-Guandique et al., 2025). You can’t stop the clock. But don’t let it take credit for damage that inactivity actually did.

How to Fix This Without Ruining Your Life

Naturally, the moment people hear “exercise builds more capacity,” they assume the fix must be brutal: more intervals, more suffering, more standing in a car park at 6am questioning your choices. It doesn’t have to be.

Both easy, sustained movement and harder efforts can send the Manager the memo he needs. A brisk walk. Cycling at a pace where you can still hold a conversation. Taking a call on your feet instead of at your desk. The stairs, every time, on principle. None of this is Instagram-worthy. But because it’s easy to recover from, you can do it constantly, and the sheer volume of “boring, easy” movement adds up in a way one brutal Tuesday session never will. Hard intervals still earn their place (a strong, efficient stimulus), but they cost more in recovery, so they work better as the seasoning than the main meal.

The real question isn’t “how hard can I train.” It’s “how much ordinary movement can I actually sustain, week after week, without hating my life.” That’s a far more useful question, and a far more honest one.

Strength training deserves a mention too, for a slightly different reason. Cardio is the stronger stimulus for the power plants themselves. Strength training maintains the actual building those power plants sit inside: your muscle. One grows the plants. The other keeps the factory standing. You need both, not because you’re training for a triathlon, but because muscle, aerobic capacity and metabolic flexibility are all part of the platform your performance sits on.

Why This Should Be an Executive Problem, Not Just a Personal One

Most organisations already treat movement as a nice-to-have: gym memberships, step challenges, a standing desk nobody actually stands at. Useful, sure. But it gets filed under “health benefit,” as though the goal is simply avoiding illness, not maintaining the actual infrastructure that performance runs on.

If a company expects people to sustain focus, manage their emotions and make sharp decisions for decades, physical capacity and cognitive capacity can’t really be treated as separate budget lines. And yet plenty of workplaces are quietly optimised to remove movement while maximising cognitive load: back-to-back meetings with no time to stand up, a five-minute walk between calls treated as inefficient, lunch eaten in front of a screen because there’s “no time.” We sit for hours discussing productivity while steadily engineering movement out of the day. It’s a genuinely funny irony, if you’re in the mood to laugh about your own workplace.

Worth asking yourself honestly: how many hours of your day pass with zero real movement? Is movement something that only happens at the gym, or is it actually built into your day? When your energy crashes at 3pm, is caffeine your automatic answer, or would ten minutes on your feet sometimes do more? Could a one-to-one become a walking meeting? Could you build a short walk between two demanding blocks of work?

And the one that matters most: does the way you work give the Power Plant Manager any reason at all to maintain the capacity you’re expecting him to hand over on demand?

The Bottom Line

We tend to treat energy like a bank account: spend carefully, don’t overdraw, top up with coffee when the balance runs low. Physiology suggests a different account entirely, one where the balance doesn’t shrink because you spent it. It shrinks because you stopped using it.

The Power Plant Manager isn’t cruel. He’s just extremely literal. He builds what you use and quietly retires what you don’t, whether you’re 25 or 65. Move regularly, and he has every reason to keep your capacity high. Stop, and he has every reason to let it drop, then act completely unbothered when you complain about being tired.

Which leads to the mildly annoying, deeply counterintuitive point of this whole article: when you’re running low on energy, doing less is often exactly the wrong move. Sometimes the honest fix is to move: not harder, not longer, just regularly enough that the Manager never has a reason to start cutting.

Movement was never just something you owe your body after a long day at a desk. It’s the memo that tells your own internal management team how much capacity to keep running. Stop treating it as time stolen from performance.

It is performance.

This article is part of our ongoing exploration of Sustainable Performance through the lens of human physiology.

Author: Giorgio Bruins

Date: September 2026

Sources

Perry, C. G., & Hawley, J. A. (2018). Molecular basis of exercise-induced skeletal muscle mitochondrial biogenesis: Historical advances, current knowledge, and future challenges. Cold Spring Harbor Perspectives in Medicine, 8(9), a029686.

Dirks, M. L., Wall, B. T., Snijders, T., Ottenbros, C. L. P., Verdijk, L. B., & van Loon, L. J. C. (2012). Bed rest reduces metabolic protein content and abolishes exercise-induced mRNA responses in human skeletal muscle. American Journal of Physiology-Endocrinology and Metabolism, 303(9), E1085–E1092.

Distefano, G., Standley, R. A., Zhang, X., Carnero, E. A., Yi, F., Cornnell, H. H., & Coen, P. M. (2014). Skeletal muscle mitochondria in the elderly: Effects of physical fitness and exercise training. Journal of Clinical Endocrinology & Metabolism, 99(9), 3536–3544.

Abrego-Guandique, D. M., et al. (2025). The impact of exercise on mitochondrial biogenesis in skeletal muscle: A systematic review and meta-analysis of randomized trials. Biomolecular Concepts, 16(1).