I also made up languages when I was young-I don't remember how the first one went, but the second one I started when I was about twelve and my father was in grad school so there was a bit of linguistics talk around the house, and his textbooks (he was in anthropology, not linguistics). I had just figured out what case and tense were because I had bought a nineteenth-century Latin textbook at a used bookstore, so when I discovered there were languages with fifteen cases and you could form cases by altering the middles and beginnings of words as well as the ends, well, my language had to have those things. And as for tense, mood, voice, and aspect-pages and pages of these forms.

Needless to say, I only wrote a few short poems in this language and never memorized it.

Maybe that's why I remain charmed by Czech even after I don't "need" it anymore...