The classic book on being a more effective executive by focusing on the things that matter. One note: you'll need to overlook the obvious sexist references to managers as "he", given that this book was written over a half-century ago. But the advice is sound and timeless for managers from any background.

From Amazon:
The measure of the executive, Peter Drucker reminds us, is the ability to "get the right things done." This usually involves doing what other people have overlooked as well as avoiding what is unproductive. Intelligence, imagination, and knowledge may all be wasted in an executive job without the acquired habits of mind that mold them into results.
Drucker identifies five practices essential to business effectiveness that can, and must, be learned:

• Management of time
• Choosing what to contribute to the practical organization
• Knowing where and how to mobilize strength for best effect
• Setting up the right priorities
• And Knitting all of them together with effective decision making

Ranging widely through the annals of business and government, Peter Drucker demonstrates the distinctive skill of the executive and offers fresh insights into old and seemingly obvious business situations.

This book changed my life (well, professional anyway), dramatically improving how I approached building support and delivering on new ideas. If you haven't already checked it out, do so. Now! This one is a must-read for how to be effective in today's business environment. Many thanks to one of my great mentors, Mike S, for introducing me to it.

From Amazon:
Millions worldwide have read and embraced John Kotter’s ideas on change management and leadership.
From the ill-fated dot-com bubble to unprecedented M&A activity to scandal, greed, and ultimately, recession—we’ve learned that widespread and difficult change is no longer the exception. It’s the rule. Now with a new preface, this refreshed edition of the global bestseller Leading Change is more relevant than ever.

John Kotter’s now-legendary eight-step process for managing change with positive results has become the foundation for leaders and organizations across the globe. By outlining the process every organization must go through to achieve its goals, and by identifying where and how even top performers derail during the change process, Kotter provides a practical resource for leaders and managers charged with making change initiatives work. Leading Change is widely recognized as his seminal work and is an important precursor to his newer ideas on acceleration published in Harvard Business Review.

Needed more today than at any time in the past, this bestselling business book serves as both visionary guide and practical toolkit on how to approach the difficult yet crucial work of leading change in any type of organization. Reading this highly personal book is like spending a day with the world’s foremost expert on business leadership. You’re sure to walk away inspired—and armed with the tools you need to inspire others.