oh that book singlehandedly changed my working life! Back in the 90's the company I worked at (A large multinational software company who was getting raked over the coals for creative accounting) gave a copy to all staff - I think the purpose was to get everyone just to shut up and put up with the cheese... instead most of the top sales people ended up going elsewhere to find new cheese :)
It taught me I can believe in myself and not put up with a whole lot of $#!T, to trust in myself and take a leap.. I've now never been afraid to leave a job that doesn't sit well or match my own morals and ethics.
For such a tiny quick and easy to read book... it was one of the most influential things in my life!