There’s a strange feeling when your brain is screaming “GO” and your body simply says “No.” Not “I’m tired” or “this is hard”—just a full stop. No power, no signal, no response.

It happened to me twice in very different ways, but both taught me the same lesson: willpower has limits when your energy systems are tapped.

The Push-Up Shutdown

I was coming off the back of a 6,000-meter swim—a brutal, unfamiliar distance for a sprint freestyler like me, who’s used to 2,000 meters max, spread over two hours with plenty of rest. My body was already protesting. So when I was asked to drop down and do push-ups after that kind of volume, I tried.

And then I failed.

I could do three push-ups. Then nothing. I was on the ground, pushing with everything I had, and nothing moved. Not even a tremble forward. After a moment’s rest, I could squeeze out one more—barely. It felt like each rep was a coin I didn’t have to spend.

That wasn’t laziness or weakness. That was acute muscular failure—ATP gone, phosphocreatine drained, nervous system blunted. The tank wasn’t empty—it was bone dry.

The Backpack Breakdown

The second time it hit me, I wasn’t even at practice. I was walking across campus with a few textbooks in my bag—something dense I liked to read between classes. The load wasn’t ridiculous, but it was heavy enough that by the time I was halfway through my walk, my legs started giving out.

I wasn’t tired in the traditional sense. I just literally couldn’t lift my foot to take the next step. I had to stop, rest, and will myself to keep moving.

I had experienced central and peripheral fatigue in the pool and gym before. But this was different. My glycogen stores were probably low, my nervous system was overworked, and the physical stress finally overwhelmed the wiring.

When Your Body Says Stop (Even If Your Mind Hasn’t)

I’ve heard people say, “The mind always gives out before the body.” And maybe that’s true—for most. But in my case, I don’t think I’m built like that. I’ve pushed through injury, fatigue, discomfort, and pressure. When you are so used to overcoming, some barriers, don’t seem like blockers.

What I experienced in these moments wasn’t mental weakness. It wasn’t doubt. It was total physiological failure. My mind was still fully engaged—I wanted to move, I meant to move—but nothing happened. No power to the muscles, no signal to execute. It was like flipping a light switch in a blackout.

That’s how I knew this wasn’t about willpower. This was biochemistry, and my system had run out of fuel.

Running Into Limits Teaches You Where They Are

In both cases, the lesson was clear: the body runs on chemistry and electricity. When your muscle cells run out of ATP, when your motor neurons stop firing efficiently, when glycogen is gone and metabolic byproducts are stacked up, the body hits a wall. And no amount of grit can break through it in that moment.

You can rest and recover and fight again—but there are limits you only find by running into them headfirst.

And if you’re lucky, you’ll walk away with a story

What Was Happening After I Did Some Reasearch

After digging into this further, it became clear: I wasn’t just tired—I had fully depleted my immediate energy systems (ATP and phosphocreatine), drained my glycogen stores, and overloaded my nervous system. These aren’t mindset problems. These are physiological red lines.

Here’s how I prepare differently now:

Fuel early, fuel often: Carbohydrate availability matters. Glycogen depletion is real, and it doesn’t care how mentally tough you are. I have further noticed when I have eaten heavy carbohydrates for the three days prior to a rough passage, sea sickness can be non existent. Yet, when my reserves are low, even moderate seas can be quite overwhelming.

Recover like it’s part of the workout: Sleep, nutrition, hydration, and cooldowns are not optional—they’re operational requirements. How do I make a greater attempt to recover? I would not have depleted these reserves in the first place.

I still believe in pushing limits. But now I do it with a clearer understanding of how those limits work—and how to recognize when I’ve crossed one.