Perhaps one of the worst strategies for promoting physical activity is to start by accusing the body of failing for working exactly as it was selected to work: avoiding unnecessary expenditure.
Exercised, by Daniel E. Lieberman, confronts the idea that voluntary exercise is the natural state of humanity and a sedentary lifestyle, a recent degeneration of character. For most of human history, movement has been linked to food, movement, care, work, play and social life. Running on a treadmill to improve a future marker is an extraordinary—and not always intuitive—cultural invention.
The reading offers no excuse to remain inactive. It offers a more useful explanation for building movement into life.
If the body saves energy by default, the environment needs to give movement reason, access and continuity.
Exercise and physical activity are not the same thing
Physical activity is any bodily movement that raises energy expenditure. Exercise is a planned, structured, and repeated form of movement, usually directed toward health, capacity, or performance. Our ancestors were physically active; that does not mean they trained out of abstract obligation.
The distinction matters because we moralize a modern solution. When someone cannot sustain gym sessions, running, or classes, we conclude that discipline is missing. Perhaps the format carries a high cost, little immediate reward, low perceived competence, and no social function. The problem may lie less in the behavior than in the design.
Lieberman shows that rest was also part of the lives of populations without modern furniture. Sitting, squatting and talking were not born with the office. The contemporary problem is different: many hours immobile, little postural alternation and opportunities for movement removed from everyday life.
How the ideas connect
Saving energy was an advantage
Energy has always been limited. A calorie allocated to movement cannot be used simultaneously for growth, reproduction, immunity, maintenance, or storage. Avoiding effort with no foreseeable benefit was not laziness; it was biologically economical.
Today, the cost of movement remains immediate, while many benefits are delayed and invisible. A session takes time now; risk reduction accumulates over years. Stairs are tiring today; functional capacity protects a future that is hard to feel. This asymmetry makes generic advice fragile.
The body also adjusts behavior to its state. Poor sleep, low energy availability, pain, illness, overload, and stress change readiness. Not every resistance to exercise should be overcome. Some signals need to be heard; others can be addressed with a smaller, more feasible dose.
Sitting less helps; moving more helps more
Public health guidelines recommend that adults accumulate 150 to 300 minutes of moderate aerobic activity per week, or 75 to 150 vigorous minutes, plus strengthening on at least two days. They also emphasize that some movement is better than none and that sedentary time should be limited.
Large observational studies associate greater physical activity with lower mortality risk and suggest that meaningful amounts of movement can attenuate part of the risk linked to prolonged sitting. This does not make exercise an absolute antidote or prove causality in every association. It does support a robust direction: building movement and capacity is more productive than chasing a perfect posture.
We also need to avoid two extremes. Sitting is not smoking; dose, context, and total movement matter. At the same time, one hour of training does not automatically erase every consequence of an otherwise motionless day. The whole routine plays a part.
From concept to decision
Health does not require turning everyone into an athlete
Sport shows how much the body can adapt. Public health needs to remember that the effective dose is not the maximum dose. For an inactive person, walking for ten minutes, getting up regularly and doing two simple strength sessions can represent a real transformation.
Progression protects continuity. Tissues, coordination, and cardiorespiratory tolerance need gradually increasing exposure, adjusted to the individual response. The book itself acknowledges in its notes that increasing running by 10% per week did not prevent injuries in the cited trial. When starting out becomes a test of courage, delayed muscle soreness, shame, and exhaustion compete with a reward that still feels distant. The person learns that movement is punishment.
The chapter on aging extends this reasoning. Lieberman presents the active grandparent hypothesis: helping younger generations may have favored a long life linked to movement. This is an evolutionary hypothesis, not an obligation to remain productive in old age. Its practical application is to preserve concrete possibilities: standing up, getting around, carrying what is needed, and participating in social life. For older adults, the guidelines also include varied activities emphasizing functional balance and strength on three or more days a week, adapted to ability. The useful question is: “What dose can this person repeat, recover from, and build on now?”
How to give function to movement
Connect movement to something concrete: travel, play, train, find relief, or take part.
Reduce distance, cost, embarrassment and decisions required to get started.
Use companionship, commitment, and belonging as part of the intervention.
Increase the dose when capacity and recovery show there is room to progress.
Design the environment before demanding heroism
- Return movement to everyday lifeWalking for short trips, taking the stairs when feasible, pausing to move, and carrying objects reduce dependence on a perfect workout.
- Preserve choiceModality, schedule, intensity and company need to fit into life. Autonomy is part of adherence.
- Build capacityStrength and cardiorespiratory fitness make other forms of movement less costly and more rewarding.
- Measure continuity, not blameRepeatable weeks are worth more than occasional spikes followed by abandonment.
The central shift
The body prefers to conserve energy—and still needs to move
- Saving energy was an advantage
- Health does not require turning everyone into an athlete
- Design the environment before demanding heroism
An evolutionary story is not a prescription
Evolutionary explanations raise good questions, but they can become “plausible stories” that are difficult to test. The fact that a behavior was possible or useful in the past does not automatically define what a person should do today.
Contemporary hunter-gatherer populations are not living fossils, and there is enormous diversity between societies, sexes, ages and environments. Comparisons need to respect method and context. Likewise, universal recommendations must be adapted to clinical condition, disability, pregnancy, age, history and safety.
The chapter on adherence also calls for judgment. Company and commitment can help, but stories of mandatory exercise or financial penalties do not make coercion a good intervention for everyone. My approach is to build an agreement that allows people to adjust a session, report pain, and rest without humiliation. The book’s value lies less in copying an ancestral lifestyle and more in moving blame out of the center. Biology explains part of the resistance; culture and design can make movement more accessible.
What remained after the final page
We were not made for gyms. We were made by a history in which movement had purpose and rest had value. The modern task is to use knowledge, environment and culture to produce a combination that our daily lives no longer deliver alone.
This requires less preaching and more architecture: walkable places, time, security, access, company, experiences of competence and tolerable progression. For some, the path will be sport. For others, dance, movement, play, strength, trail or care.
The best physical activity is not the most natural one. It is the one that finds enough meaning to continue.
References
- Exercised: Why Something We Never Evolved to Do Is Healthy and Rewarding.
Educational content. People with symptoms, clinical conditions or limitations should individualize the activity with qualified professionals.