“If you haven't read hundreds of books, you are functionally illiterate, and you will be incompetent, because your personal experiences alone aren't broad enough to sustain you.”
General Jim Mattis - AKA Call Sign Chaos
Read, read, read. I cannot emphasize this enough. Fiction, non-fiction, memoirs, technical manuals, I don't care. You should always have a book you're reading, and you should have a list of books ready to go. If you need audiobooks to make it work, get audiobooks. Personally, I start with audiobooks for a lot, and if the book is impactful enough on me, I order a physical copy for my library and I make a notebook for the highlights and my thoughts (because you can't remember everything you read but you can refer to the highlights in your notes).
A parting thought - some books are like tools. You can read and re-read them later in life to remind yourself - of your values, of your direction, of your trade. Other books are one-and-done, and that's okay. They open your mind to the new ideas, so you can get back to work.
If you truly don't know where to start, may I recommend the Marines Commandant's Professional Reading List, organized by category. Pick one and go from there.