If a brain is exercised properly, anyone can grow intelligence, at any age, and potentially by a lot. Or you c... — Michael Merzenich

If a brain is exercised properly, anyone can grow intelligence, at any age, and potentially by a lot. Or you can just let your brain idle - and watch it slowly, inexorably, go to seed like a sedentary body.

Author: Michael Merzenich

Insight: Most of us understand that muscles atrophy without use, but we treat our brains like they're somehow exempt from the same rule. We assume intelligence is fixed at birth, something you're either born with or you're not. The reality is messier and more hopeful: your brain is genuinely plastic, capable of rewiring itself throughout your entire life. The catch is that this plasticity works both ways. Neglect it, and the decline is real—not dramatic overnight, but noticeable over months and years. What makes this particularly relevant now is how easy it's become to coast intellectually. We consume information passively, scroll familiar feeds, let algorithms do the filtering for us. It's comfortable. But comfort is exactly the condition that leads to mental stagnation. The brain responds to challenge the way muscles respond to resistance training: it strengthens, builds new connections, and expands capacity. That could mean learning something completely new, engaging with ideas that genuinely confuse you, or having conversations with people who think differently than you do. The hopeful part isn't just that decline is preventable—it's that improvement is always possible. You're never too old to get sharper. But like physical fitness, it requires actual effort. The choice between growth and decline isn't something that happens to us; it's something we actively make, every day.