Your doctor has a scale. It measures weight. Your doctor has a blood pressure cuff. It measures pressure. Your doctor has labs. They measure things in your blood. And with all of these tools, your doctor is measuring exactly one thing: disease.
Is something wrong? Is the number outside the range? If yes, it's a problem. If no, you're fine. That's the entire framework. It's useful for catching pathology, but it's useless for understanding how your body actually works. Two people can have identical blood pressure, identical cholesterol, identical weight, and move through the world in completely different ways. One climbs stairs without grabbing the rail. The other holds her breath at the top. One stands on one leg while putting on pants. The other falls over. Same labs. Totally different bodies.
This is what I mean by function versus disease. Your doctor is trained to find what's broken. They're not trained to assess what's working. And if you're not testing function, you're flying blind.
I've been testing function for years. Not because I'm obsessed with optimization—I'm not. But because if you're going to change something about how you move or eat or recover, you need to know where you're starting from. You need a baseline. You need to know which problems are actually problems and which ones are just stories you've been telling yourself.
Here are the tests I use. They take sixty seconds each. You can do them right now, in your living room, in your work clothes.
The Blind Balance Test
Stand in a doorway or next to a wall where you have something to grab if you fall. Close your eyes. Stand on one leg. How long can you stay there? Count the seconds. Your goal isn't to be perfect—it's to know where you are.
Healthy nervous system function? Most people under fifty can do this for thirty seconds. Over fifty? Thirty to sixty is solid. Over sixty seconds? You're doing better than ninety percent of your peers. Less than ten seconds? Your proprioceptive system needs attention. Your feet aren't talking to your brain the way they should be.
This test reveals something your doctor's scale never will: whether your nervous system is receiving accurate information about where your body is in space. This is fundamental. If your brain doesn't know where you are, everything falls apart. Balance, coordination, injury prevention—it all depends on this signal.
The Grip Strength Squeeze
You don't need a dynamometer, though they're cheap. You just need something to squeeze that tells you whether you're crushing it or barely managing it. A tennis ball works. Your own fingers work.
Grip strength predicts longevity better than almost any other single metric. It predicts cardiovascular health. It predicts metabolic health. It predicts cognitive function. And here's the thing: most people never test it because there's no marketing campaign for grip strength. Nobody sells you a product to improve your grip strength. So nobody thinks to measure it.
Squeeze as hard as you can for five seconds. Notice the effort. Notice if you feel strong or weak. If you're over fifty and you can't crush a tennis ball hard enough to make it actually compress, that's data. Your grip is part of your whole-body strength capacity, and if it's weak, the rest of you probably is too.
The Big Toe Audit
Take off your shoes and socks. Stand on a flat surface. Look at your big toe. Try to lift it off the ground while keeping all your other toes flat. Can you? Can you do it on both sides? How much control do you have?
This sounds ridiculous. It isn't. Your big toe is your ballast. It's how you balance, how you accelerate, how you stabilize your ankle and your whole kinetic chain. If you can't activate your big toe independently, your foot is half asleep. And if your foot is asleep, your whole system is compensating.
Most people can't do this. That's not a judgment—it's data. Years of cushioned shoes, elevated heels, and no barefoot movement will atrophy the muscles that should be doing this work. But here's the good news: it's easy to wake up. Spend two minutes a day lifting your big toe on and off the ground, and within two weeks you'll feel a difference in your balance.
The Battery Gauge Test
This is my favorite because it's honest. Close your eyes. Get a sense of how much energy you have right now, in this moment. On a scale of one to ten, with one being "I need to lie down" and ten being "I could run up four flights of stairs and not breathe hard," where are you?
Most people answer with a number and then realize they have no idea what their baseline is. They're living at a five or a six and don't realize it because they've never felt a nine. That's the insight. The battery gauge test is just calibration.
Come back to this number. Do it every morning. Keep track. After two weeks, you'll have a sense of your normal range. Then you'll start to notice the things that change it. That meal made me a four instead of a six. That sleep gave me a seven. That stress dropped me to a three. You're learning the inputs and outputs of your own system.
This is software debugging. You're not trying to be perfect. You're trying to know yourself.
Here's What You Do This Week
Run all four tests on Monday. Write down the numbers. Actually write them down, don't just remember them. Where can you balance on one leg? How hard can you squeeze? Can you lift your big toe? What's your battery gauge?
Then just live. Don't change anything. Don't go on a diet. Don't start a new training program. Just do the tests again on Friday. See if anything moved. Probably it won't—one week is short. But you'll be surprised how often people say, "Oh, I actually could hold the balance longer. I was less tired at the end of the day. I actually felt my big toe working today."
Come back and do this same test in thirty days. Your baseline will probably improve. Your grip might get stronger. Your balance will probably be steadier. Your battery gauge will probably stay a little higher. Not because you did anything crazy, but because the act of paying attention changes the game. Your nervous system gets the signal: hey, we're measuring this. This matters. Wake up.
This is what I mean by testing function. Not tracking calories. Not optimizing macros. Not chasing numbers on a scale. Just: do I work better? Do I feel better? Can my body do more? Is my system moving in the right direction?
Your doctor is great at finding what's broken. But you're the expert on what works. You're just probably not paying attention. These tests take sixty seconds. Do them. Write them down. Come back in a month.
That's how you get to know your operating system.
— Moose