I honestly do not think that most leaders think about engagement enough.
My favorite source on engagement is Professor William Kahn. He suggested that engagement was related to three key factors: Meaningfulness, safety, and availability.
Meaningfulness relates to the perceived benefits of investing energies into work roles. Think about it – if you feel your work role is meaningful, you will feel valued and useful - you will be more engaged.
Safety reflects your own personal comfort in expressing yourself truthfully without fear of retaliation or other negative consequences. Engagement represents the ultimate connection between self and role: thus the honest expression of self is a key engagement component.
Availability is your perception of the accessibility of resources to do your work. If your people's physical and emotional energies are depleted, you will disengage because you feel that work is too demanding.