These songs may come straight from the heart with the Holy Spirit creating the melody. They may be hymns of praise and prayer from the hymn book. One might read a favorite Psalm, or one you have never looked closely at before. To sing to the Lord is to worship God in melody. To wait in God's presence is simply to be there to love Him.
Meditation differs in that during it our mind is very active.
To meditate is to think about spiritual themes in reference to God. Only once in Scripture do we find God specifically promising success and prosperity. We must take time to listen. Here we listen for direct orders from our Heavenly Father concerning the activities of our day. In order for listening to be effective though we must respond by doing what He instructs us to do.