Claude Cartigenese of the “Polyglot Project” compiled a huge 600 page document with stories from many language learners around the world who explain how they became polyglots. Some of the linguists in the book include, Moses McCormick, Benny Lewis and Steve Kaufmann.
The “Polyglot Project” received great feedback, and as a result was downloaded several thousand times. There is a hard copy of the book. The book is also available free as a PDF.