Every head has a critic in it. Train that voice into a coach instead of firing it.

The internal critic is not going anywhere, and trying to silence it usually just makes it louder. It exists because part of you is paying attention to standards, which is not a bad thing on its own. The problem is the delivery. A coach says the same accurate thing and then adds what to do about it, and that second half is the only difference that matters.

When the voice starts, let it name the problem and then demand the rest. Ask what the next step is. If it cannot produce one, it was being harsh rather than useful.