'ZEST' equates to zing, enthusiasm, energy, gusto, eagerness, zeal and fervour. It also connotes a tang, a sharpness.
It's the opposite of bland.
And Zest: How to Squeeze the Max out of Life is exactly that.It's more than just a book on personal development. There are an awful lot of those. Zest is a catalyst, a spark that ignites your remembering of what makes you, in a word, you. It drives you to rethink, rejuvenate and reinvent. It also contains a touch of the revolutions. 
Have you, as a grown-up, fallen into the trap of becoming a Groan-up? You know you should try to make the best of things, but oftentimes you don't know what your "best" is anymore. It's strange. You used to know. What happened? Was it the years of social conformity? There is a whole beige generation out there - a generation that has lost its identity and forgotten who they once were - buried...