Here are a few resources on burnout.
Helping Senior Pastors Overcome Depression and Burnout: Written to help pastors specifically, but has so many good insights both theologically and practically for overcoming burnout.
How I Recovered From Burnout: 12 Keys to Getting Back: Short article written from ministry/Christian perspective.
Why Do We Work Too Much?: Good, practical thoughts on reducing work load. Too much to do contributes greatly to burnout.
Can’t Even: How Millennials Became the Burn Out Generation by Anne Helen Petersen: