Harvard Scientist Reveals Why We Hate Exercise (Our Ancestors Never Did It, and That’s Actually Normal)

Most people think they hate exercise because they’re lazy or unmotivated.

Turns out, there’s an evolutionary reason why getting off the couch feels so hard—and it has nothing to do with willpower.

In fact, understanding how our ancestors moved (or didn’t move) might be the key to finally making peace with physical activity.

Evolutionary biologist and anthropologist Daniel Lieberman recently unpacked why humans are “exercised about exercise“—and his insights might change how you think about fitness forever.

Exercise Is a Modern Invention (And Your Body Knows It)

The word “exercise” comes from Latin, originally meaning “to train.” Soldiers exercised. Students did math exercises.

But today, exercise has two contradictory meanings: voluntary physical activity for health and feeling anxious or upset. Lieberman finds this duality revealing.

It’s part and parcel of the strange concept of exercise. It’s this modern idea of doing voluntary discretionary physical activity for the sake of health and fitness. But we don’t do it often. Most people don’t do it ’cause they want to, they do it because it helps stave off death and decrepitude.

Nobody in the Stone Age “exercised.” They were physically active when necessary—hunting, gathering, escaping predators. Optional five-mile morning jogs? Unthinkable.

Exercise is a bizarre modern behavior, and our instincts are wired to resist it.

The Paradox: Everyone Wants To Exercise, Almost Nobody Does

According to CDC data, only 20% of Americans meet minimum exercise recommendations—150 minutes per week.

That means 80% of people fail to hit even baseline activity levels, despite knowing exercise is beneficial.

The paradox is that most things that are good for us we kind of want to do. But exercise is the reverse. It’s something that we all know we want to do, it’s good for us, and yet a lot of us have a hard time doing it.

When asked why they don’t exercise, people cite two main reasons:

• No time: Between commutes, jobs, kids, and responsibilities, finding 30 minutes feels impossible
• It’s unpleasant: Sweating, discomfort, fatigue—exercise doesn’t feel rewarding in the moment

Both reasons are legitimate. Both deserve compassion, not shame.

Stop Blaming Yourself For Hating Exercise

Lieberman argues we shouldn’t make people feel guilty for struggling with exercise. Inertia is completely normal.

Our ancestors conserved energy whenever possible because calories were scarce. Unnecessary movement meant fewer resources for survival and reproduction.

We shouldn’t make people feel bad for having those instincts. Instead, we should help them figure out ways to overcome those instincts because we live in a world where we now, because we’ve mechanized everything, we no longer have to be physically active. We now have to choose to be physically active. And that’s not so easy.

Modern life has mechanized movement out of existence. Cars, elevators, desk jobs—everything conspires against natural activity.

Fighting millions of years of evolution requires strategy, not willpower.

Debunking Exercise Myths

Lieberman identifies several pervasive fitness myths that confuse people:

Myth: Our Ancestors Were Natural Super-Athletes

Many believe hunter-gatherers could effortlessly run ultra-marathons or perform incredible feats of strength.

Reality: Running long distances was just as hard for them as it is for modern humans. They sweated, cramped, and struggled—they just valued the activity enough to push through.

When they run an ultra marathon, it’s just as hard as when I were to try to run an ultra marathon. They do it not because it’s easy for them. They do it because they value it, they think it’s worth doing.

This myth stems from problematic “noble savage” stereotypes and does harm on multiple levels—dehumanizing indigenous populations while making Westerners feel inadequate.

Myth: There’s One Perfect Type of Exercise

Paleo diets, barefoot running, CrossFit supremacy—fitness culture loves declaring one approach superior.

Reality: Human bodies are adaptable. Different approaches work for different people and goals.

Myth: It’s Normal To Be Less Active As You Age

Many accept declining activity levels as inevitable.

Reality: Hunter-gatherers maintained activity throughout life. Physical decline is largely cultural, not biological destiny.

Ironman vs. Tarahumara: More Similar Than Different

In 2012, Lieberman witnessed two seemingly opposite endurance events: Hawaii’s commercialized Ironman World Championships and a traditional Tarahumara foot race in rural Mexico.

Surface-level differences were striking:

• Ironman: High-tech gear, $20,000 bikes, specialized nutrition, massive crowds
• Raráhipri: Everyday clothes, sandals, homemade corn-based “Gatorade,” small community gatherings

But fundamentally? Nearly identical.

Both involved extreme endurance (Ironman’s 140.6 miles vs. Raráhipri’s 40-50 miles). Both featured betting, prizes, cheering, victory, and defeat. Both represented personal journeys undertaken by a small percentage while most people watched.

It made me realize that oh yes, there are some differences between sort of more modern, commercialized western forms of endurance physical activity. But this is something basic and fundamental that all cultures do. And actually I think what makes us similar is greater than what makes us different.

How Active Were Our Ancestors, Really?

Scientists measure activity using Physical Activity Level (PAL)—total daily energy expenditure divided by basal metabolic rate.

Here’s where different groups fall:

• Bed rest: 1.2
• Chimpanzees: 1.4
• Sedentary Americans: 1.6-1.7
• Hunter-gatherers: 1.9-2.0
• Subsistence farmers: 2.1-2.2
• Tour de France cyclists: 3+

Surprisingly, sedentary Americans are more active than chimpanzees—our closest relatives evolved to conserve energy too.

Hunter-gatherers weren’t superhuman. They were moderately more active than modern desk workers, not endurance machines.

Why “Training” Confused Hunter-Gatherers

When Lieberman asked Native American runners how they trained for races, they looked confused.

Through a translator, he explained running five miles daily to prepare. Their response?

Why would you run if you didn’t have to? Because their life is their training.

When asked when they run, the most common answer: “To chase a goat.”

Physical activity was woven into daily survival, not compartmentalized into “workout time.”

Your Body Spends Most Energy Just Existing

Basal metabolic rate (BMR)—energy spent on basic bodily functions—accounts for roughly two-thirds of daily calorie expenditure.

Lieberman’s example: He burns about 1,600 calories daily just maintaining his body. His morning five-mile run? Only 500 additional calories.

When food was scarce, those 500 calories represented a significant trade-off. Spending energy unnecessarily meant less for survival and reproduction—the only things natural selection cares about.

This is why avoiding unnecessary activity feels instinctive. For most of human history, it was adaptive.

The Takeaway: Work With Evolution, Not Against It

Understanding evolutionary context doesn’t excuse inactivity—it empowers smarter approaches.

Key insights:

• Your resistance to exercise is normal—stop feeling guilty
• Hunter-gatherers weren’t superhuman—they just had no choice but to move
• Modern life requires intentional movement—it won’t happen accidentally
• Find activities you value enough to do despite discomfort—just like the Tarahumara

Lieberman’s goal isn’t to glorify ancestral lifestyles or shame modern ones. It’s to help people be less exercised about exercise by understanding why it feels hard—and developing compassionate, evidence-based strategies to overcome evolutionary inertia.

Because in today’s mechanized world, choosing to move is one of the most unnatural—and most necessary—things we can do.