The Bible. 66 books, 40 authors, written over a period of 1500 years, originally written in 3 languages, on 3 different continents, and one singular theme from cover to cover - Jesus.
It's a book I often take for granted. I have been in ministry for 10+ years. I have 4 or 5 Bibles in my house, an app on my phone, and I work at a church that has 100 of them in the building. I read it, honestly most days I do because it's my job too. I prepare lessons on a weekly basis and that keeps me in it. I've always struggled with making time for Scripture because I want to, not because I need too for a lesson or sermon. Reading has never been something I just enjoy to do. It's always been a battle. I've started reading 30+ books and finished maybe 5 of them. I've been really trying to "schedule" time to just sit, be still (tough), and spend time reading my Bible.
No other text brings life to dead bones like Scripture can. I truly belive the Bible hold the answers to all questions and it's the primary tool God uses to speak to us. He has something to say to you as well, pick up a copy and have a listen.