When you do write, what prompts it? Find out what the impetus is and then arrange to have lots of it. (Fo instance, mine is attention, so I have lots of beta readers and publish everything I write on the Internet.) NaNoWriMo isn't the ideal writing environment for everyone.
Write down ideas for things to write about as you have them. Pick the best/most original/etc. the next time you have an opportunity to write. If you are short on time and find that you tend not to be pleased with the ideas you use, this is probably more workable than just writing about everything you think of.
Do one pass of editing on each thing you write, after letting it sit without looking at it for at least a few days. This will give you practice at drawing your attention to things you find "overwritten" after the fact; hopefully you'll eventually nip those patterns in the bud before they make it into your writing.
Generic advice that doesn't address anything specific you said: Do not delete things you write, ever. If you are tempted to do this, bury them somewhere in the deepest recesses of your computer, but never delete.
Do not delete things you write, ever.
Why? (I currently delete most of my writing.)
An exercise:
Name something that you do not do but should/wish you did/are told you ought, or that you do less than is normally recommended. (For instance, "exercise" or "eat vegetables".)
Make an exhaustive list of your sufficient conditions for avoiding this thing. (If you suspect that your list may be non-exhaustive, mention that in your comment.)
Precommit that: If someone comes up with a way to do the thing which doesn't have any of your listed problems, you will at least try it. It counts if you come up with this response yourself upon making your list.
(Based on: Is That Your True Rejection?)
Edit to add: Kindly stick to the spirit of the exercise; if you have no advice in line with the exercise, this is not the place to offer it. Do not drift into confrontational or abusive demands that people adjust their restrictions to suit your cached suggestion, and do not offer unsolicited other-optimizing.
To alleviate crowding, Armok_GoB has created a second thread for this challenge.