Seriously, The Bhagavad Gita is probably one of the first books i would to recommend any one to read....Its a total lifechanger....It has great principles with very convincing examples.It inspires me when i am down, and is my refuge in times of distress. The upanishads too, are a great souce of strength. All you people out there, get urselves a copy of the Gita - Its far from being just a religious book...
But one small reminder - The principles may be kind of new and subtle, but fuse them into your paradigm, and you shall see the changes.