God tells us that his yoke is easy and his burden is light. So, if we are straining and fall under the yoke and the burden, it's not God's...I don't mean that life is never hard or that our homes must always be filled with only sunshine and roses. But I still mean that if we are straining and falling and sinning under the strain of the yoke, it's not God's yoke...Yes, we will suffer, but I have learned that it is indeed possible to suffer joyfully. Burnout is not suffering joyfully.
I love this quote Jennifer at Conversion Diary put in her great article about discerning and overcoming burnout. It has a lot of great suggestions for many aspects of life. It's a good way to examine any area of life that is giving you problems, not just burnout.