Having suffered a nervous break-down, melt-down, burnout, I have done a bit of study into the causes of this all to common experience, here a few thoughts and findings...
BURNOUT
DEFINITION
Burnout is a loss of energy and fulfillment in workers previously highly motivated. It is fatigue coupled with despair, afflicting especially those in the helping and serving professions who give much more than they receive. It differs from mere fatigue in being coupled with hopelessness and, unlike clinical depression, it does not arise entirely from within the person. Burnout is psychosocial and its causes are both subjective and external[1]
Burnout means to deplete yourself, to wear yourself out by striving to reach unrealistic expectations imposed by yourself.
Causes
People who are emotionally extroverted are more likely to burnout
The on-going gap between the ideal and the day to day reality proves to be a huge strain, as you have to emotionally deal with unfulfilled expectations.
Leslie Francis suggests that younger or more recently appointed ministers are at greater risk of burnout than older longer serving ones as they have not had yet developed strategies for dealing with it.
Israel Galindo calls year seven the year of recharge or burnout
The size transition from Pastoral (50-150) to Programme (150-300) size church is a recognised point of burnout in ministers. (see A Rothauge, Sizing up a Congregation for New Member Ministry).
Burnout is the chronic stress of trying to square the expectations of others about who I am and what I do (G Read 
