Here are some good posts for pastors (and others too) about burnout:
What Is Burnout and Why Is It So Dangerous? – David Murray (Crossway)
Preventing Pastoral Burnout – David Murray (Crossway)
How to Stay in Ministry Over the Long Haul – David Murray (Crossway)
4 Cultural Factors That Contribute to Our Epidemic of Burnout – David Murray (Crossway)
A good preacher must be committed to this, that nothing is dearer to him than Christ and the life to come.