I highly recommend this book, The Richest Man in Babylon, since it has helped me to save and invest money.
For a perspective on people’s different lives ranging from janitors, entrepreneurs, nurses, factory workers, etc. read this book. Working: People Talk About What They Do All Day and How They Feel About What They Do
I have used this book since I was an undergraduate for designing spacecrafts. Space Mission Analysis and Design, 3rd edition (Space Technology Library, Vol. 8)