Mark Twain famously said that writers should replace the word "very" in their manuscripts with the word "damn" instead. Then, editors would remove the word and all would be as it should. It gets really easy to stick extra words into manuscripts, and it doesn't stop at "very." Have you learned the art of brevity yet?
Just the Facts, Ma'am
Extra words are just one problem that keeps you from mastering brevity. I don't have a big issue with very, but I do have a problem with just. My characters are always just going to do this and just thinking about that, until the word has completely lost all meaning. Once you know you use certain extra words, it's easier to spot them and rout them out of your manuscripts.
But in order to truly master brevity, you have to take things one step further. You have to learn how to avoid over-writing and repetition. You can't simply eliminate that extra word that you always tend to over-use. You've got to get rid of all the extra words.
Read and re-read every single scene in your book, and ask yourself what it's doing there. Does this scene compel the story forward? Does it give us some new information? Does it reveal something about one of the characters? If the answer is no to all three, then you clearly don't need that scene in your book.
You also don't want to over-reveal something. If you tell a reader something once, you don't necessarily have to keep repeating this information. Once you make it clear your character has a problem with substance abuse, for example, the reader shouldn't be dragged through a dozen nearly-identical party scenes. Repetition and over-revealing become boring very quickly. The reader just wants to learn something new.
This is why overly-embellished descriptions can be a little wearying as well. To truly master brevity, you must keep your descriptions brief. Impart the necessary information, and move on. Relay information, keep going. This is brevity, and for many authors it's been their bread and butter. Even if it's not the style you want to bring to your readers, learn how to do it. Make deep cuts in your manuscript. Learn how to edit yourself, because it's a skill that can only help you become a better writer in the end.