Starting a new job often begins with a blissful honeymoon phase, in which someone's best work is consistently produced. Inevitably, this comes to an end sooner or later, when the flaws of the job gradually start to reveal themselves, and it's natural that an employee's passion may fade away once...
I liked this article about igniting passion in your workforce. I am not sure I would use the word passion - I might replace it with focused, energized, engaged, self-motivated. When these elements occur, employees tend to show high levels of personal initiative and proactivity.
When missing, people tune out, lean outward, find other ways to become self-actualized than at work, and generally act bored and disinterested (not engaged).
One of my constant efforts as a high school girls basketball coach and management consultant around hiring/retention is to continually be taking the pulse, and developing actuion plans to keep the passion high.
What do you do frequently with your team beyond reviewing daily to-do activities?