Improv Wisdom by Patricia Ryan Madson
This is an excellent first book on improv to read, if you're new to improv or even just wondering whether or not improv might be for you. And, this is also a great book to read if you've done improv from years, and want to see how improv might apply to other facets of your life.
Patricia masterfully ties together fundamental improv concepts, and shows how the wisdom of improv applies to the rest of your life. It's a pretty cool idea once you start getting down to the nuts and bolts of it. Concepts like "yes, and" take on a whole new meaning when you start to realize... hmm, the reason this works on stage is because it's really how people are supposed to live.
I highly recommend checking this book out, and reading through the basic concepts. If nothing else, you'll have a few resources to de-stress your life, as Patricia has probably lived these concepts out in her own life, and speaks from experience.
There are a lot of high-level books out there about how to manage an improv troupe, to how to perform Harolds, to how to be funny. This book isn't overly intellectual, and broad enough to apply to whatever form of improvisation you do--whether that's serious dramas, short form comedy, or making presentations to your sales force.
Check it out.