In the category of "success" or "personal improvement" my answer has always been the same:  "The Magic of Thinking Big" by David Schwartz.  This book was first published in 1959, but remains a classic.  It is filled with timeless wisdom on the topic of success, and directly confronts the issue holding most people back in life; their lack of a big picture.  The book is filled with nuggets on how to think big, dream creatively, and manage one's attitudes while turning defeat into victory. 

Some of my favorite quotes are:

Life is too short to be little.

Believe, really believe, you can succeed and you will.

The more successful the individual, the less inclined he is to make excuses.

Resolve to live until you die.

It's better to wear out than rust out.

Einstein taught us a big lesson.  He felt it was more important to use your mind to think than to use it as a warehouse for facts.  

Action cures fear.

No one ever does anything worthwhile for which he is not criticized.

People are alike in many, many more ways than they are different.

Look at things not as they are, but as they can be!

These quotes are just a sample of the gold dripping from the pages of this timeless little book.  As you can see, it contains some powerful stuff.  If you choose to read it, I trust it will be of great assistance in your life and career.

Think big!    Dream big!  Fulfill your destiny!!