I often hear fellow athletes and fitness enthusiasts bemoan that they missed a workout.

There’s a lot of reasons people have this attitude. Maybe someone’s counting calories, and they are too tired to burn their allotted amount today. Maybe they have a strict training plan, and they feel obliged to stick to it. Maybe someone’s worried that if they stop they’ll never go back because they’ve hated the workouts, hated the nutrition, and only do it for the looks—or the speed.

You can’t “miss” a day of training, especially if you’ve been training so much (or eating so little) that the reason you missed training today is because you’re exhausted. Days of rest are when the body does the most growing, and prepares for the next phase of exertion. What “missing” a workout really means is that the body has time and space to develop. But our identities have become so fixated on the overt part of training—exercise—that we often work out to the detriment of our health, our bodies, and ultimately our athletic goals.

This happens with most runners. The emphasis gets put on weekly mileage, and people destroy their knees. This is because weekly mileage is largely an arbitrary measure: a lot of the times it is socially arbitrated—what amount of mileage does “a marathoner” do?—and ignores the biomechanical, psychological, and social realities of the particular body that is being trained.

It’s not the miles that makes you develop. It’s the recovery after the miles.

And it’s not just a matter of waiting a day, either. It’s a matter of resting a day.

In order to rest, the body has to shift gears: during training, one part of the nervous system is activated (also known as the sympathetic nervous system, or SNS). Rest is generated by the parasympathetic nervous system, or PNS. If, for whatever reason, on our day of “rest” we became stressed out at work, with our family, or because we’re “missing” a workout, we’re not resting at all.

Truly grasping and internalizing the importance of rest is one of the things that makes or breaks an athlete—literally. A recent study found that olympic non-medalists and olympic medalists had surprisingly consistent attitudinal differences. Contrary to what you would expect, olympic medalists didn’t train harder. The difference was that Olympic medalists didn’t overtrain. While the non-medalists increased their training volume and intensity (to try and become medalists), they ended up overtraining and underperforming because of it.

We’re seeing the social system at play: increasing volume and intensity is doing nothing for these non-medalists, ironically except to reassure them that they’re doing something. Their belief systems (which are based on their identities) tell them that the way to get better is to train more. But the truth is that they need to rest more.

Instead, what happens is they train more, so they underperform—but because of their belief system, that only galvanizes them to train even more. It is the very act of trying to catch up to the medalists, that makes it impossible for the non-medalists to do so.

Herein lies the importance of cultivating a particular mindset: it isn’t just that the medalists didn’t overtrain. It’s that they grasped the reason why they shouldn’t. In other words, the difference between the medalists and non-medalists is in the mind—in the mindset that causes one group to consistently overtrain, while causing the other group to consistently err on the side of caution.

Rest does not constitute missing a workout. If you want to change your injury rate, or your fitness, start by changing your ideas. If a particular set of ideas gets you to the gym, but do nothing for your injury rate or fitness, you need different ideas. And if those new ones aren’t working, toss them like a set of dirty underwear. Only then will you see the training start to take effect towards the goals that you have set for yourself.