We’ve all seen it. One person runs a marathon with ease, while another struggles to jog around the block. It’s tempting to chalk it up to laziness or willpower, but the truth, as highlighted in a thought-provoking TED Talk, is far more complex.
Science reveals that our ability to exercise, how easy or hard it feels, is deeply wired into our biology. It begins with something called “exercise response variability,” a term used to describe how individuals’ bodies and brains react differently to physical exertion. This isn’t just about muscle mass or stamina; it’s about how our brains perceive effort and reward.
At the core of this difference is dopamine, the “motivation molecule.” Some people naturally produce more dopamine when they exercise, which makes them feel good, driven, and accomplished. Others generate less, meaning they don’t get the same emotional payoff, and as a result, exercise feels like a chore, not a reward. For these individuals, every movement feels heavier, every mile longer.
Genetics also plays a role. Studies show that some people are born with higher aerobic capacity or more efficient muscles. They burn energy differently, recover faster, and fatigue less quickly. For others, genetic factors can cause exercise to trigger discomfort, breathlessness, or even anxiety. It’s not a failure—it’s biology.
But environment matters too. If you grew up in a household that prioritized movement, I walking, dancing, playing sports, you likely associate exercise with fun and confidence. On the other hand, if exercise was tied to punishment, body-shaming, or fear, it’s no surprise that it feels like torture today.
Yet despite these challenges, the most hopeful part of the TED Talk is this: your brain is adaptable. You can retrain it. By choosing movement that feels enjoyable and reducing the pressure to “perform,” you can shift how your body responds over time. Walks in nature, dancing in the living room, or even cleaning the house can count as physical activity, and can slowly build your tolerance and joy for movement.
So next time you’re tempted to compare yourself to a gym addict, pause. Your exercise journey is uniquely yours. And just because it’s hard now doesn’t mean it will always be.
You’re not broken. You’re built differently.
