Concept
Non-Striving
2 books in the library reach for this idea - each in its own way. When independent authors converge on one concept, it usually deserves attention.
Full Catastrophe Living
How this book uses it: In meditation, not trying to achieve anything or go anywhere. This is hard for achievers. The goal is to be, not do.
Wherever You Go, There You Are
How this book uses it: Most of life is about achieving, improving, getting somewhere. Meditation is the opposite - being fully where you are without trying to change anything.