Another idea on using mistakes to grow is learning to quantify your mistakes. If you were to take a test and get a 97 or 98, you would think you were pretty awesome and had a great mastery of your subject, wouldn't you?. Of course you would. But musicians let one mistake ruin a song or exercise for them. When you're working on scales and technique, one exercise may contain 500 notes. I have an exercise for working the guitar neck that has 3500 notes, and that's not that unusual. A practicing musician may easily play 50,000-100,000 notes in a day. So (I hate to be this meticulous, but) measure the number of notes in your exercises and allow yourself 2% error without penalty, without holding yourself back for mistakes. That means in that big guitar exercise I allow myself to make 70 mistakes (wrong notes, fingerings, broken rhythm) without penalizing myself or holding myself back from upping the speed. The idea here is to balance mistakes with what you're doing right and address the speed versus accuracy fight. This is useful for all but especially necessary for nit-picky types. You can always tighten up to 100% perfection for a performance.
Concentrate your emotions into the message of your music. Let the listener, not the looker, learn the most from your performance.