People think of that complexity as an expression of our capacity for abstract thought. We believe our brains are so complex because of the wonders we can build in our minds. Make no mistake, we can build wonders in our minds but what we have neglected is that those wonders are boot strapped on top of motor control. The first purpose of the brain is to guide movement.~ Rafe Kelley from, https://www.evolvemoveplay.com/the-why-of-movement-practice/
And the second purpose it to solve problems in the physical world. (How do I go over there? How do I avoid that danger? How do I get food?) To solve problems you need to be able to define what the problem is. You define any problem by imagining some desired state (I am over there. I have avoided that danger by running. I have eaten that food.) and then looking for options that can get you from the current state, to the desired state. So it turns out that the better your imagination is, the better you can be at solving problems. Faced with endless options, you mind turns out to be really good at heuristics—making estimations in advance with limited knowledge (prejudice can be a good thing; assuming snakes are not friendly is an excellent heuristic.) All of which makes possible the beauty and diversity of our lives. Fortunately, we have a capacity for reason atop all of that which enables us to make choices so the possibility of beauty and diversity can be our a reality. I digress.
Back to Kelley’s point, if the entire edifice of our minds is built upon that first purpose, what happens if we starve the mind of the physical engagement?