Built, Not Born (Mostly): What Resilience Teaches Us About Fitness
Updated: Oct 8
Everyone knows someone who seems unbreakable. They get knocked down by a job loss, an injury or a bad year, and they're back up while the rest of us are still lying on the floor. The same person often shows up to the gym in the rain, bounces back from a tweaked knee, and never seems to burn out. So the question arises: are they just built differently, or did they build themselves?
This article looks at what the evidence says about resilience, whether it can be taught or is mostly genetic, and what that means for how we train our bodies.
What do we mean by resilience?
Resilience isn't toughness or an absence of struggle. Psychologists generally define it as the process of adapting well in the face of adversity, trauma or significant stress. The key word is process. It's not a fixed trait you either have or lack, but a pattern of responding that shows up differently across situations. Someone can be resilient at work and fragile in relationships, or the reverse.
Fitness has a close parallel in the idea of adaptation. You apply a stressor (a heavy squat, a long run), you recover, and the body rebuilds slightly stronger. Both resilience and fitness are about how a system responds to stress and what it does afterwards.
The case for genetics
The "born with it" argument has real evidence behind it.
Twin studies, which compare identical twins (who share all their DNA essentially) with fraternal twins (who share about half), consistently find that resilience-related traits have a meaningful heritable component. Estimates for traits like emotional stability, stress reactivity and mental toughness commonly land somewhere between 30% and 50%. Genes involved in the stress response system, including those affecting cortisol regulation and serotonin signalling, appear to influence how strongly and how quickly people react to threats.
Temperament also shows up early. Some babies are calmer and more adaptable than others before they've had much chance to learn anything, which hints at a biological starting point.
The case for learning
But "30 to 50% heritable" has a flip side: it means half or more of the variation is not explained by genes. And heritability doesn't mean fixed. It describes how much of the difference between people in a given population is linked to genetic differences, not how much of your own outcome is locked in.
Several lines of evidence point toward resilience being trainable:
Skills-based programmes work, modestly. Reviews of resilience training in schools, workplaces and the military generally find small to moderate improvements in coping, wellbeing and symptoms of anxiety and depression. They are not miracle cures, and results vary a lot by programme quality, but the effect is real.
The skills involved are learnable. Reframing negative thoughts, regulating emotion, building social support, solving problems actively and maintaining a sense of purpose can all be practised. These are the active ingredients of cognitive behavioural approaches, which have strong evidence behind them.
Experience shapes us. Research on adversity suggests that moderate, manageable challenges can build coping capacity, while overwhelming or chronic stress tends to erode it. Dose and support matter enormously.
Environment can switch genes up or down. Epigenetic mechanisms mean that life experience influences how genes are expressed. A genetic tendency toward stress reactivity may be harmful in a harsh environment and neutral, or even beneficial, in a supportive one. Some researchers describe this as differential susceptibility: the same sensitivity that makes someone vulnerable to bad conditions makes them respond especially well to good ones.
The verdict
Genetics sets the starting point and the range. Experience and training determine where you end up within that range.
Resilience isn't purely taught and it isn't purely inherited. Genes load the dice, so some people begin with a higher baseline of stress tolerance and others start lower. But the evidence for skills, supportive environments and graded exposure to challenge is strong enough that nobody should treat their current resilience as a life sentence. People with a less favourable genetic hand often have the most to gain from deliberate practice, and they can end up more resilient than someone who started high and never developed their skills.
The most honest answer is both, with a bias toward optimism: you cannot choose your genes, but you can meaningfully influence what you do with them.
Now apply it to fitness
Fitness research tells almost exactly the same story, and it makes the resilience picture easier to see.
Genetics shapes how much you respond. The HERITAGE Family Study, a landmark project, put sedentary people through identical endurance training. Improvements in aerobic capacity varied hugely: some people gained a great deal, while a minority gained very little. Roughly half of that variation in trainability appeared to run in families. Similar patterns show up for strength and muscle growth.
But nearly everyone improves in something. Even "low responders" on one measure often improve on others, such as blood pressure, insulin sensitivity or mood. And a person who doesn't gain much aerobic capacity from one programme might respond better to a different type, volume or intensity of training. Non-response is often a mismatch between person and programme, not proof of a ceiling.
Training is the thing you control. Consistency, progressive overload, sleep, nutrition and recovery are the fitness equivalents of coping skills, social support and purpose. They don't erase genetic differences, but they dominate the outcome for most people for most of their lives.
What this means in practice
Stop comparing your rate of progress to others. If a friend gains strength twice as fast as you, that may be partly biology, not discipline. Compare yourself to your own past.
Treat the dose as a design variable. In fitness and in resilience, moderate, recoverable stress builds capacity, while too much too soon breaks it. Progress your training the way you would build tolerance for hard things: gradually, with recovery built in.
Train the mind alongside the body. The ability to keep showing up when motivation drops is itself a resilience skill. Habit design, realistic goal-setting, self-compassion after missed sessions and a plan for setbacks all predict long-term fitness more reliably than raw willpower.
Use fitness as resilience training. Hard workouts are a safe laboratory for practising discomfort tolerance, staying calm under strain and recovering afterwards. There is good evidence that regular exercise improves stress regulation and mood, so the benefits can transfer into everyday life.
Recover like it matters. Resilient systems, physical or psychological, are defined by how they bounce back, not by how hard they can be hit. Sleep, rest days and social connection are part of the training, not a reward for it.
Experiment if you're not responding. If a programme stalls, change the stimulus before concluding that you're "just not built for it."
The bottom line
Resilience and fitness share a structure: a genetic foundation that influences your starting point and your ceiling, and a large, trainable space above and below it that you can shape through practice, environment and support. The people who seem unbreakable usually got a helpful biological head start, but they also built habits, relationships and skills that anyone can work on.
You can't pick your genes, but you can pick your next small, manageable challenge, and then recover from it.
A note on the evidence: figures like the 30 to 50% heritability range are estimates that vary by study, measure and population, so treat them as ballparks rather than precise values. If you're managing a health condition or returning from injury, check with a clinician before changing your training.
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