ANYTHING, even if you put your mind to it. Nobody can do “Anything.” Nobody can fly by flapping their arms, jump across the Atlantic Ocean, or dribble a waffle. In fact, nobody can do “anything” that other people can do. Not everybody can sink a half court shot, hit a major league home run, or solve Fermat’s theorem. Some people can kill themselves trying and never hit the high note in The Star Spangled Banner or execute a triple axel.
Why do people repeat this facile obvious half-truth? And why do they act like you are clubbing baby seals if you challenge it? Nobody’s saying “give up kids, it’s all futile,” but I think kids are better served by a little verisimilitude. Shouldn’t it be sufficient to say, you know kids, you are probably capable of being really good at one thing. You should figure out what that is and learn how to do it, and then you might do SOMETHING. Something meaningful, and something nobody has done before.
Because everybody on the planet - except, apparently, you - is competent n the usage and understanding of coloquial speech and understand what the phrase means.
Do you get upset when people say “it’s raining cats and dogs” or “I’m boiling!”? Or do you berate them for repeating facile obvious untruths?
That’s what the phrase "you can do anything’ actually means. Nobody interprets it as meaning you can actually do the impossible, except to be obtuse.
Anyway, I think it’s better to be prepared to attempt anything and be restricted by the bounds of the possible, than it is to start from what’s known to be possible and try to nudge out the boundaries.