It’s a curse and a blessing. The only way to get good at anything is to always take a critical look at what you’ve done, and then tweak, change, and improve on what you’ve done before. Anybody who improves does it. Sometimes it’s not easy (or pain-free), but it’s essential to progress.
The trick is to silence that valuable inner critic when it’s showtime, and just before showtime, because that’s not when you need the critique. Charlie Parker said it best: “You’ve got to practice, practice, and practice. And then, when you finally get up to the bandstand, forget all that and just wail.”
That kind of critique is just one of the many things expert practicers do. There are lots of others to be found in The Practice of Practice, or in the shorter version with more pictures, Pracctice Like This.
Here’s George Carlin’s critique of his 1992 performance on David Letterman (video of his appearance below the notes). It’s fascinating to see the mind of a genius critique himself. The nuance of changing “lobster tails” to “rack of lamb” is probably lost to most, but to Carlin, “rack of lamb” is funnier. I think I agree. Here are his notes:
The bit from Carlin’s notes starts at 6:20
The Practice of Practice 