Wolpert explains that his group tried to reverse engineer how humans control movement. What makes this difficult, and what is the example he uses to demonstrate the concept?

Heyyy! drugs are not good for u. and u should know that! it can injure you or hurt u! drugs itself sounds dangerous! i'm pretty sure u heard many stories about the danger of drugs! even if u are addicted or just want to, pls don't do it! it's harmful even though maybe u don't realize it. until u realize it, it's going to be too late, and i don't want that to happen to u or to anyone. drugs shouldn't be your top priority, just think about it, why do u want to use drugs? u can do so many other things that can relive u, or things u like to do. i might not get what situation u are in, but drugs can't be the thing on your mind all the time, what if the ppl that cares about u gets hurt because, one day they get a call that u are in a hospital; injured or they can have a knock on there door telling them that u past away or something happened. it's not cool and upsetting, obviously i'm not someone who can force u to not do anything u want to do, but pls keep in mind, always think about the people who cares about u, and if u see a child younger than u by a lot, or just younger, u would tell them to not do drugs(maybe) if u do tell them that, u realize it's bad for them, which means u abounds do it either bc its bad. no matter the age, u shouldn't be doing stuff that would hurt u, bottom line is, i can't tell u what to do, u do u, but i'm younger than u, and just want to say pls don't get hurt.