Think about your best kitchen knife. The more you use it, the duller it gets. Eventually, you have to sharpen it. But if you don’t use it, and you just leave it in a drawer for six months, it’ll be just as sharp as the day you put it away.
Now think about your brain. Your brain and that knife have nothing in common.
I often talk about how great it is that our brains can grow and rewire in response to challenges, much in the same way that muscles grow when you exercise. And don’t get me wrong – this is a good thing. It means we’re not stuck the way we are. We can learn, grow, and improve. We can become more skilled, more intelligent, and more creative. But there is a downside that’s rarely discussed.
I’ve hinted at it before. I did mention in my post about brain muscles that cognitive skills, just like the muscles in your arms and legs, can atrophy with disuse. I have highlighted the “use it or lose it” principle of neuroplasticity. And I’ve warned students that the mastery path is a muddy slope. But it’s time to really get clear about this.
You can improve, yes, but you can also get worse. Think about your physical fitness. What would happen if you just stopped exercising? How fit would you be a year from now? Five years from now? Well, your brain works the same way. If you don’t challenge your brain with mental workouts – learning new things, practicing old skills, and solving difficult puzzles – you won’t just stagnate; you’ll actually lose intelligence.
Trust me, I’ve been there. Between the ages of 23 and 27, that’s exactly what happened to me. I didn’t challenge myself intellectually, and my mind got weaker as a result.
This also applies on the micro-level of learning new skills. You can get better, but you won’t stay better unless you keep at it. On the fixed-mindset – growth-mindset continuum, there are people who are growth-minded enough to know that they have to work hard to get good at something, but then they mistakenly believe they no longer need to practice. And then a week or a month or a year later, that hard-earned skill is gone.
So having a growth mindset, isn’t just about believing that you can improve; it’s also about remembering that you can regress.
This is part of the reason I encourage kids to make good use of summer. And it’s a major reason that I personally practice relentless learning. Unlike a kitchen knife left in a drawer, my brain won’t stay sharp automatically. I have to use it to keep it sharp.

Chris Loper has been working as a tutor and academic coach since 2014, racking up over 10,000 hours of experience supporting students.
Along with Greg Smith, Chris is the cocreator of Parenting for Academic Success (and Parental Sanity) – a five-part course offered every summer.
Chris writes the popular self-improvement blog Becoming Better, where he also offers habit coaching, helping busy adults with habit formation and productivity.
Chris’s most recent endeavor combines his academic and habit-formation expertise to help students thrive in college. Visit SmartCollegeHabits.com to learn more.
In 2021, he published a humorous memoir titled Wood Floats and Other Brilliant Observations, a book that blends crazy stories with practical life lessons, available on Amazon and through most local bookstores.
He lives in Issaquah, WA where he is the owner of South Cove Tutoring.