From Wikipedia:
Think and Grow Rich is a 1937 motivational personal development and self-help book by Napoleon Hill and inspired by a suggestion from Scottish-American businessman Andrew Carnegie. While the title implies that this book deals with how to get rich, the author explains that the philosophy taught in the book can be used to help people succeed in all lines of work and to do or be almost anything they want.
You can read it below, or you may download the pdf here.