Christian people who really want to serve the Lord with willing, servant hearts sometimes neglect their own well-being. Jesus showed his closest followers, his apostles, that it was important to get away from the crowds, get some rest, and spend time alone with God.
The apostles gathered around Jesus and reported to him all they had done and taught. Then, because so many people were coming and going that they did not even have a chance to eat, he said to them, "Come with me by yourselves to a quiet place and get some rest." So they went away by themselves in a boat to a solitary place. (Mark 6:30-32 TNIV)
You would take care of your best friend so that he or she could take care of others. You would try to understand him, and comfort her, and strengthen that friend in every way possible. You need to do the same thing to yourself, as well!
Christian writer Frederick Buechner said, "A bleeding heart is no help to anybody if it bleeds to death." That means not only taking care of yourself physically, but feeding yourself with divine nourishment from the Word, being merciful to yourself, and accepting the bread of life from Jesus.