Understanding changes me, but acting changes the world around me. So acting must be preceded by thinking to create positive change. Improving through change is not an occasion, it is a lifestyle.
Acquiring a new language has showed me the need to "do" on a practical level. Adequacy is absorbing the language through different sensory inputs. Seeing and hearing the words only primes me to write and speak. Mastery demands output: employing the new vocabulary and structure. Exercising my pronunciation, conversation, and notation skills allows me to integrate with the language.
The humble sea squirt: rudimentary animal; has a nervous system; swims around in the ocean in its juvenile life. And at some point in its life it implants on a rock and the first thing it does after implanting on that rock, which it never leaves, is to digest its own brain and nervous system for food. So once you don’t need to move, you don’t need the luxury of that brain.