"And he said unto them, Come ye yourselves apart into a desert place, and rest a while: for there were many coming and going, and they had no leisure so much as to eat" (Mark 6:31)
In "Biblical Perspective" Dr. Gayle Woods writes:

In Jesus Only, Vance Havner said, “We need to come apart and rest awhile, and if we don’t come apart, we will come apart — we’ll go to pieces!” Stress can destroy a person’s life physically and spiritually. Headaches, heart problems, and stomach problems are just a few symptoms of this concern. Burnout is a problem for those who are in some form of Christian ministry. Whether a person is overworked or if life situations bring a lot of stress, it is essential that proper rest, relaxation, and nutrition be maintained in order to preserve good health. Jesus the Great Physician was concerned about the physical well-being of His disciples as well as their spiritual well-being. The disciples and Jesus clearly were overworked and overcommitted. The demands of the people upon their ministry were too great. A balance was needed, and the Doctor prescribed a short vacation.

Source: Miracles of Jesus, Adult Teacher's Insights, page 5.