Paredit is so good that even after taking a break from Lisp for years, as soon as I opened up an .el file to do some Emacs customisation, the muscle memory was fully intact and I was able to perform structural edits without even thinking about which keys I pressed. I try not to write too much Lisp these days, because I inevitably become depressed at how clumsy it is to manipulate syntax in the languages I use more commonly.