The One Formula That Explains Every Breakthrough (and Every Burnout)

What do vaccines, saunas, and tempo runs have in common?

They’re all stressors—and they all make you stronger, until they don’t.

In biology, this is called hormesis: the principle that low to moderate doses of stress trigger a positive adaptation. It’s why cold exposure, UV rays, and training can make you more resilient. I would casually refer to this as the “what doesn’t kill you makes you stronger” phenomenon. But only when the dose is right. Otherwise, the dose determines the poison.

Go too far, and that same stress becomes destructive:

• Too much time in the heat can lead to heat exhaustion

• Too much exposure to cold can cause hypothermia and frostbite

• Too much sun exposure causes skin cancer

In moderate amounts, these stressors sharpen us and boost our vitality. In large amounts, they break us.

Training works in the same way.

The body loves to be in a state of balance, called homeostasis. While at rest, things like blood sugar, blood pH, heart rate, and breathing patterns stay within a tightly regulated range, with rare deviations.

Every run you do throws the body into temporary chaos. Heart rate spikes to deliver more oxygenated blood to muscles. Acidity starts to build up in the bloodstream. Body temperatures rise. Fluid is lost through sweat. Fuel stores get depleted. Muscle fibers incur microdamage with every stride. Even an easy run leaves you dehydrated, depleted, and mildly damaged.

That’s not a bad thing. It’s the point.

Exercise-related stress disrupts homeostasis, and the response to that disruption is where the magic lies. Because what happens next isn’t just recovery. It’s an overcorrection.

During recovery, the body rebuilds. Then it fortifies.

This is the principle of supercompensation: given the right stress and enough time, your body doesn’t just bounce back. It levels up. But here’s the catch: that adaptation is on a clock.

Wait too long before stressing the system again, and the gains fade through a process called detraining. Stress too soon, and you haven’t rebuilt yet. You just dig a deeper hole.

Workouts only create the potential for gaining fitness. Those gains are realized in the recovery process.

The Growth Equation

I see too many runners obsess over mileage, reps, and splits, which measure the stress. However, they only pay lip service to the other side of the equation.

Here’s the truth: the only training that you benefit from is the training you can recover from.

Most injuries, illnesses, and plateaus aren’t just the result of too much running. They’re also the result of too little recovery. Overtraining is almost always under-recovery in disguise.

And that’s a hard truth for distance runners to accept.

We’re wired to push. To believe that more is better. Taking a rest day feels lazy. Sitting on the couch feels like a failure. In my opinion, too many high-achieving distance runners walk around with the scales tipped in the direction of stress, away from recovery.

It’s a dynamic balance you have to get right. Push hard enough, often enough, and your body pushes back, with broken bones, inflamed tendons, and mental burnout. That’s not weakness. It’s a warning: the dose got too high.

Brad Stulberg and Steve Magness coined “the growth equation” in 2017, and it has stuck with me ever since. It’s the most succinct description of a fundamental theory in exercise physiology:

Stress + Rest = Growth

If one side of the equation is missing, nothing works.

In the rest of this newsletter, I’ll focus more on the “stress” side. I’ll dedicate future newsletters to recovery. But let’s be clear: your gains depend on getting both sides right.

When thinking about stress, the key questions are: How much? How often?

Aim For Just Manageable Challenges

I’m a big believer in “just manageable challenges.”

That’s the sweet spot—not the hardest thing you can survive, but the hardest thing you can adapt to.

Jack Daniels, the famous distance running coach, said that all stress must have a purpose and training should strive for the least amount of stress possible to achieve a given adaptation.

It’s not the heroic push that leaves you curled on the infield (although occasionally, you need this). It’s a well-calibrated dose that allows your body to improve without pushing it to the brink.

The body responds well to gentle nudges, not torturous pokes.

You don’t need to chase constant progression every session. Don’t test your limits every time to find the edge—leave that last frontier to be explored on race day.

Your training should match where you are today, not where you wish you were.

As one of my college coaches, John Oliver, used to say: “We don’t need to swing for the fences every workout. A base hit is good enough.”

Enough base hits, stacked over time, win the game.

There are No Shortcuts

A common question many runners ask: “How often should I do hard efforts?”

If you look around and survey top training groups, most of them will do two hard workouts per week plus a long run. The rest is easy mileage.

On average, does that formula work pretty well? Sure. Is that the optimal answer for everybody? Nope.

The frequency of hard workouts really depends on how long it takes your body to recover. When it comes to balancing stress and recovery, the primary leverage point is time. You can’t rush biology.

I can guarantee that getting in the ice bath after each training session will not shorten the required recovery window from four days to two days. The body can’t be hacked like that.

There are no shortcuts for glycogen replacement, tissue repair, or immune system restoration. Sleep, nutritious food, time, and a calm mind are all your allies. Trust your body’s innate capacity for growth and recovery.

You can’t fast forward adaptation. But you can ruin it by being impatient.

Most runners overestimate what they can accomplish in a week and underestimate what they can build in a year. They chase short-term spikes instead of long-term compounding.

So after a workout, give yourself time. Let your biology catch up to your ambition.

Deposits and Withdrawals

Let me conclude with a metaphor I draw upon all the time. Training is a lot like managing a bank account. Every run with adequate recovery is like making a small deposit. It might not feel like much at first, but if you keep showing up and making those deposits consistently, your fitness account starts to grow. Over time, you build a healthy balance.

At the beginning of a training cycle, when you’re young and inexperienced, your balance is low. If you try to make a big withdrawal too soon (like hammering a workout you’re not ready for), you risk going into debt.

In running terms, that “debt” might look like burnout, injury, or getting sick. Your body just doesn’t have enough in reserve yet to cover the stress.

But as you build fitness, that account grows. You earn the right to spend a little more. You can tolerate harder workouts and more mileage. That’s because you’ve built a buffer—a savings account of aerobic strength, durability, and recovery capacity.

Just like real savings, fitness doesn’t come from one massive deposit. It comes from stacking small ones day after day.

So don’t rush the process. Build your balance slowly, protect your account, and know that the best runners aren’t the ones who spend wildly—they’re the ones who invest wisely.

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