And wow, is it frustrating.
I mentioned last week that my cousin, a professional musician, had replaced his old stage piano and given me the old one. I implied but never stated explicitly that I took many years of piano lessons as a child, ending about 30 years ago. Off and on since then I've picked up some music and banged away at it in a practice room—I was a music major for a year, after all—but I haven't done anything of significance in such a long time I'd almost forgotten what it was like.
So I've been practicing again, and it's incredibly frustrating.
Take Petzold's simple Menuet in G that ever kid learns. In only two or three playings, I could get my right and left hands to sail through it independently at about 132 to the quarter note. Putting them together even at 108 was excruciating, however. Fingers on one hand would fire out of sequence while the other hand stammered along like a wounded cicada; transitions I'd practiced two dozen times would fall apart for no reason; my mind would go blank for half a second causing the whole edifice to fall. And this is the 16-bar Petzold menuet, not a freakin' prelude and fugue, FFS.
Yes, this is normal, I know. It's just that I'd forgotten. And also that I'm doing pieces every 10-year-old can do. But after only a couple of hours, I got two Petzold menuets back to fighting strength (at least until the next time I practiced), so it's more encouraging than discouraging.
And finally, I'm experiencing the chagrin that adults have always felt. Remember when your parents told your teenaged ass you'd kick yourself for giving up piano/horseback riding/competitive Yahtzee when you got older? They were right.