"And he [Jesus] 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, KJV.

The ministry gets busy (if you don't believe me, ask anyone in it). There have been days where I have had so much going on that I didn't even have the opportunity to eat lunch until 2:30 (my lunch break is usually at 12:15). Both of my parents are in the ministry, and I know they've run into this situation many times as well. Serving God gets busy, but the wonderful thing is God knows we need rest. God always gives us respite when He knows we need it. We should never feel guilty about taking a break after working ourselves into the ground, because we need rest! We're human, and, as a result, our flesh is week. God gives us the opportunity to rest as a reward for serving Him. So, enjoy His rest. Don't abuse it or ignore it, but enjoy it. He loves you too much to let you burn out.