Which book instantly changed you? Both for personal and business benefit.

What is one book that had the deepest impact on you the instant you were done (or in the process) reading it? Why was the book so significant?

The 4 Hour Work Week - Time Ferriss
Confirmed to me that I wasn't the only person who thougt that the western European/America concept of working for someone else, in an office, for a set number of hours per week wasn't the future.

Crush It - Gary Vaynerchuk
This along with one of his keynotes was one of the things that gave me the final push to leave corporate.

Rework - Jason Fried
How to do business the opposite way to how you were taught in school/corporate.

The Power of Now by Eckhart Tolle
You'll learn the real meaning of spirituality and the importance of the present moment.

The Road Less Traveled by M. Scott Peck
Most indepth book on love, psychological and spiritual development that I have ever read. Clear and straightforward.