When the Bible says that ravens brought Elijah food, it doesn't mean they took his order, flew through the local fast food restaurant, and then delivered his meal. Ravens are scavengers. They brought little bits of meat and bread to Elijah. What's more, the water in the brook from which he drank would have been somewhat polluted. It wasn't an easy situation by any stretch.
How easily Elijah could have said, "Well, Lord, I don't really want to be in this crummy little place, drinking river water. I kind of like being in front of people. I like the limelight." But the Lord was preparing Elijah for something beyond his wildest dreams. Not long after this, Elijah would be standing on Mount Carmel in that great showdown with the false prophets (see 1 Kings 18:20-40).
Sometimes we don't like where God has put us. We say, "Lord, I don't like this situation. I don't like where I am. I want to do something great for You. I want to make a difference in my world." Maybe the Lord wants you to be effective right where you are. Maybe He wants you to take advantage of the opportunities in front of you and be faithful in the little things. Who knows what God has in store for you?
If God has you by some muddy little brook, so to speak, just hang in there. Be faithful, do what He has already told you, and wait on Him and on His timing. God will do something wonderful for you or with you. Just be available and open to do what He would have you to do.