Zest

In positive psychology, zest is one of the 24 strengths possessed by humanity. As a component of the virtue of courage, zest is defined as living life with a sense of excitement, anticipation, and energy. Approaching life as an adventure; such that one has “motivation in challenging situations or tasks”. Zest is essentially a concept of courage, and involves acquiring the motivation to complete challenging situations and tasks.

http://en.wikipedia.org/wiki/Zest_%28positive_psychology%29