The Goal by Eliyahu M. Goldratt

What it is about:

In the form of a novel, following a plant manager, the goal walks you through the essentials of operations management, push and pull systems and dynamic queueing systems.

Why it changed my thinking:

It opened my eyes to a whole new class of behaviors not captured by traditional calculus or algebra, gaining insight about the complexities of dynamic behavior in discrete systems, building my intuition and making me aware of the role that variability, random or deterministic, plays in the performance of everyday systems, from Starbucks to Disneyland to complex semiconductor manufacturing.

Where to get it:

(Note, if you buy from the links here, I get a little commission back)