When you take a flight, shortly after embarking on your journey the flight attendants do a spectacular presentation on what to do in case of an emergency. Of course, one of those emergencies is a drop in cabin pressure, in which case 4 oxygen masks will drop from the ceiling. In this, they tell you if you are traveling with children to take care of putting the mask on yourself and THEN take care of the children. Now see, to some people that confuses them. Our instinct tells us to sacrifice ourselves before children. However, in this case you will not be able to help that child if you have not made precautions for yourself.
I think we need to apply this concept in other areas of our life, both spiritually and physically. How can we lead our children to live a Godly life where they are prayerful and seeking him in everything, if we ourselves are not doing that first?
Then there is another issue...our bodies. What service are we doing for our children if we do not take care of our bodies? Do they not deserve to have us with them as long as possible? Of course they do. I do not know one person who says "Oh, I don't care if I live to see my grandchildren". I guess there are those bent on self-destruction that may, but for most, we want to be there for our kids (and grand-kids and to live to a rightful old age). Problem is we allow everyday duties to be put in front of caring for ourselves and therefore we are hurting our children (and ourselves).
So, remember, to properly care for children you need to first take care of yourself!