This is from a talk that Elder M Russell Balard gave a the October 2006 General Conference-O Be Wise

He gave six points on how to serve wisely

Fifth, we need to thoughtfully allocate our resources of time, income, and energy. I would like to let you in on a little secret. Some of you have already learned it. If you haven’t, it’s time you knew. No matter what your family needs are or your responsibilities in the Church, there is no such thing as “done.” There will always be more we can do. There is always another family matter that needs attention, another lesson to prepare, another interview to conduct, another meeting to attend. We just need to be wise in protecting our health and in following the counsel that President Hinckley has given often to just do the best that we can.

The key, it seems to me, is to know and understand your own capabilities and limitations and then to pace yourself, allocating and prioritizing your time, your attention, and your resources to wisely help others, including your family, in their quest for eternal life.