I have a strange habit of picking up college textbooks from garage sales whenever I find them and I will read through them whenever I have the inkling to learn something new. I have books over anatomy and physiology, art history, ancient Chinese history, a bunch of high level math books (calculus, trigonometry, theoretical physics, etc) American civil war, business management, Microsoft office books, Japanese language, Chinese language, Russian language, Spanish language, python coding, and I could go on and on. to me learning is a good way to keep my mind sharp and any new skills are useful in the future. the ones I read the most are any engineering based math books, Chinese and Japanese language, and management books because these specifically help me out in advancements in my career.