Not too hard. Not too soft. 85% is Just Right

Goldilocks and the three bears

She lay down in the first bed, but it was too hard. Then she lay in the second bed, but it was too soft. Then she lay down in the third bed, and it was just right.

Goldilocks fell asleep.

Too hot, too cold, too hard, too soft. The magic happens in the middle. This simple truth from a children’s story keeps appearing in surprising places - from Olympic training programs to machine learning algorithms, from ancient Buddhist teachings to modern psychology.

I first noticed this pattern while studying gradient descent in artificial intelligence. The optimal error rate for learning turns out to be precisely 15.87% - or put another way, the sweet spot is about 85% accuracy. This oddly specific number stuck with me, and I began seeing similar patterns everywhere.

An Olympic swimmer describes finding her “easy speed” - that mysterious state where 85% effort yields 100% of the results. Weight training scientists recommend working at roughly 85% of your maximum capacity for optimal strength gains. Even in meditation practices, the middle way between extreme effort and complete relaxation leads to the deepest insights.

Our culture tends to glorify maximum effort. We’re surrounded by productivity systems, optimization techniques, and exhortations to push harder. But what if sustainable excellence comes not from pushing to our limits, but from finding that elusive middle ground?

Let’s explore how this principle shows up across different domains, and what it might tell us about the nature of learning, growth, and performance.

The Mathematics of “Just Right”

The 85% principle first caught my attention in an unlikely place: artificial intelligence. When training AI models, researchers use something called gradient descent - essentially a mathematical way of helping the computer learn from its mistakes. It turns out there’s an optimal error rate for this learning: 15.87%, or in other words, getting things right about 85% of the time.

This isn’t just a convenient coincidence. In 2019, a team of psychologists and neuroscientists found that this same ratio appears in human learning. When people are acquiring new skills - whether it’s playing piano or learning a language - they learn most effectively when they’re succeeding about 85% of the time. Too much success means the task is too easy; too much failure means it’s too difficult to gain traction.

Think about the last time you were learning something new. If every attempt succeeds, you’re probably not pushing yourself enough to grow. If you’re failing constantly, you’re likely to get frustrated and quit. But that sweet spot - where you’re mostly succeeding but still regularly encountering challenges - that’s where real progress happens.

Amos Tversky, the renowned psychologist, captured a similar idea when he said that the secret to doing good research is to be “a little underemployed.” You need some slack in the system, some room for exploration and error. As he put it, “You waste years by not being able to waste hours.”

This might seem counterintuitive in our efficiency-obsessed culture. But there’s something profound here: optimal performance isn’t about maximizing effort or minimizing errors. It’s about finding that middle ground where growth happens naturally, almost effortlessly.

Finding “Easy Speed”

The idea that less-than-maximum effort might produce better results isn’t just mathematical theory - it shows up vividly in athletics. When sports psychologist Terry Newberg studied world-class performers, he kept encountering a peculiar pattern. These elite athletes, who you might expect to talk about pushing themselves to the limit, instead described moments of almost effortless mastery.

One Olympic swimmer told Newberg about discovering her “easy speed” - a state where she applied about 85% effort but got 100% of the results. It wasn’t about straining harder. Instead, she found a place of fluid, unhurried engagement. The performance was better, and paradoxically, it felt easier.

This insight isn’t new. Back in the mid-20th century, a track coach named Bud Winter was revolutionizing sprint training at San Jose State University. Winter, who had worked with Navy pilots on relaxation techniques during World War II, noticed something fascinating: runners performed better when they were relaxed rather than tense. His program produced 27 Olympians and his book, “Relax and Win,” became a quiet classic among athletes.

The same principle shows up in modern cardio training. Exercise scientists have identified specific heart rate zones for optimal training. Surprisingly, the most beneficial zone for long-term cardiovascular improvement isn’t all-out effort - it’s Zone 2, roughly 60-70% of maximum heart rate. Elite endurance athletes spend most of their training time in this moderate zone, saving the high-intensity work for specific, limited sessions.

Even in weight training, where you might expect maximum effort to reign supreme, the science points to moderation. The National Strength and Conditioning Association recommends training at about 85% of your one-rep maximum for optimal strength gains. Push beyond that too often, and you risk injury and burnout. Stay too far below it, and you miss out on growth stimulus.

The pattern is clear: peak performance isn’t about constant maximum effort. It’s about finding that sweet spot where effort and ease combine to produce something greater than either could achieve alone.

Weight Training: The Science of Optimal Resistance

Weight training isn’t just about lifting the heaviest weights possible. Over the years, scientific research has refined our understanding of this discipline. The National Strength and Conditioning Association (NSCA), founded in 1978, marked a shift towards a more scientific approach to strength training.

Central to modern weight training is the concept of the one-repetition maximum (1RM) – the maximum weight a person can lift for a single repetition of a given exercise. This benchmark serves as a foundation for designing effective training programs.

Interestingly, the NSCA’s recommendations for resistance training align closely with the principle of moderation. For developing muscular strength, they suggest performing 4-6 repetitions with at least 85% of your 1RM. This range hits the sweet spot of challenging the muscles sufficiently without overtaxing the body.

The NSCA’s guidelines also account for other training goals:

• For muscular hypertrophy (growth), they recommend 6-12 reps at 67-85% of 1RM.
• For muscular endurance, the recommendation is at least 12 reps at less than 67% of 1RM.

These guidelines demonstrate that even in a field seemingly dedicated to maximum effort, moderation and balance play crucial roles. Training at around 85% of maximum capacity allows for optimal strength gains while minimizing the risk of injury and burnout.

Key Takeaway: When designing your strength training program, aim for that 85% sweet spot. It’s challenging enough to drive progress but not so intense that it leads to burnout or injury.

Cardio Training: The Power of Moderate Effort

As we shift our focus from weights to cardio, we find an interesting twist on the moderation principle. Here, the optimal zone for long-term benefits often lies at an even lower intensity, challenging the “no pain, no gain” mentality prevalent in fitness culture.

Cardio training is typically divided into five heart rate zones based on your maximum heart rate (MHR). Surprisingly, the most beneficial zone for sustained cardiovascular improvement is Zone 2, which falls between 60-70% of MHR. This zone offers significant long-term benefits:

1. Increased VO2 Max (maximum oxygen uptake)
2. Improved aerobic threshold
3. Activation of the parasympathetic nervous system, promoting recovery and stress reduction

The key insight is that in cardio training, the most beneficial work often happens at a surprisingly moderate intensity. Zone 2, despite feeling “too easy” to many athletes, allows for sustained effort without overtaxing the body. This approach enables consistent training, promotes recovery, and yields superior long-term cardiovascular benefits.

Consider the training approach of elite marathoners. Contrary to what you might expect, these athletes spend the majority of their training time in Zone 2, reserving high-intensity work for specific, limited sessions. This moderate approach allows them to build an enormous aerobic base without burning out.

Key Takeaway: Don’t underestimate the power of “easy” cardio. Incorporate more Zone 2 training into your routine for long-term cardiovascular health and performance gains.

Flow State: The Psychology of Optimal Experience

As we move from the physical to the mental realm, we encounter a concept that beautifully illustrates the power of finding the right balance: Flow state. The idea of balancing challenge and capability as the key to optimal performance has been studied by psychologists for decades. One of the most influential findings in this area comes from Mihaly Csikszentmihalyi, who introduced the concept of “Flow” to the world.

Csikszentmihalyi’s journey began in the 1960s when he was a psychology professor at the University of Chicago. Intrigued by what makes people truly happy and fulfilled, he observed artists who would become so immersed in their work that they would forget to eat or sleep.

Through extensive research, Csikszentmihalyi identified a common experience he termed “Flow” – a state of consciousness where people are so absorbed in an activity that nothing else seems to matter. Time flies, self-consciousness disappears, and performance seems to happen effortlessly.

Central to Flow theory is the balance between challenge and skill. Flow occurs when the level of challenge in a task matches the person’s skill level. If the challenge is too high relative to skill, anxiety results. If it’s too low, boredom sets in. The Flow channel represents that optimal middle ground where peak performance and enjoyment intersect.

Real-world examples of Flow abound. Jazz musicians describe entering a state where the music seems to play itself. Athletes talk about being “in the zone,” where their actions feel automatic and time seems to slow down. Writers like Stephen King have described writing sessions where hours pass in what feels like minutes.

Key Takeaway: To cultivate Flow in your own life, seek activities that challenge you just beyond your current skill level. This sweet spot of difficulty is where you’ll find the most engagement and growth.

The Yerkes-Dodson Law: Finding Your Cognitive Sweet Spot

As we delve deeper into the psychology of performance, we encounter another principle that reinforces the power of moderation: the Yerkes-Dodson law. “Just work harder, right? Push yourself to the limit, and you’ll achieve greatness!” If only peak performance were that simple. Our brains aren’t wired like sports cars where flooring the gas pedal always results in top speed. Instead, they’re more like finicky espresso machines – the right amount of pressure produces a perfect brew, but too much leaves you with a bitter, jittery mess.

The Yerkes-Dodson law, discovered by psychologists Robert M. Yerkes and John Dillingham Dodson in 1908, suggests that there’s a sweet spot of arousal (read: stress or excitement) where we perform at our best. Too little, and we’re unmotivated; too much, and we’re overwhelmed.

The relationship between arousal and performance varies:

• For simple tasks, more arousal generally equals better performance.
• For complex tasks, there’s a point where additional stress starts to hinder rather than help.

Picture a bell curve with “arousal” on the x-axis and “performance” on the y-axis. For difficult tasks, performance rises with arousal up to a point, then takes a nosedive.

This law has been widely studied and applied in various fields. In education, it helps explain why a moderate level of test anxiety can improve performance, while excessive stress leads to choking. In sports psychology, it informs techniques for achieving optimal pre-competition arousal levels.

Understanding this concept can be a game-changer. It means that sometimes, the key to better performance isn’t pushing harder, but finding that Goldilocks zone of just-right pressure. This optimal zone keeps you engaged and focused without tipping over into stress-induced underperformance.

Key Takeaway: Next time you’re facing a challenging task, aim for the focus of a Zen master, not the frenzy of a caffeinated chipmunk. Find your personal sweet spot of arousal – engaged but not overwhelmed – for optimal performance.

The Yerkes-Dodson law reinforces our central thesis: moderation, not extremes, is often the key to unlocking our full potential. As we’ve seen across physical training, psychological flow, and cognitive performance, finding the right balance is crucial for peak performance and well-being.

In our next sections, we’ll explore how this principle of moderation extends into other areas, from creativity and innovation to leadership and decision-making. We’ll also examine how these ideas challenge certain cultural norms and how they might shape our approach to emerging challenges in an increasingly complex world.