Thinking Inside The Box.
A combination self-help and business book, Michael Port's Beyond Booked Solid focusses on scalability issues and how to expand a small enterprise.
It is filled with pragmatic tools and techniques designed to grow a business via innovation and leveraged income, but the key message is that of developing a mind-set that works on your rather than in your business.
To some extent that's just a reframing of the old adage of keeping one's eye on the big picture, but it's something that can't be repeated too often. Constantly reminding yourself and your colleagues of why you're in business (and specifically what customer needs you meet by doing something better than anyone else) is crucial to evaluating everything that you do day to day.
If your marketing tactic du jour, your latest product development or your inter-departmental meeting isn't centred on that, they're not worth your time and resources.