From: Matthew 4:18-22
The First Disciples Called
 As He (Jesus) walked by the Sea of Galilee, He saw two brothers, Simon who is called Peter and Andrew his brother, casting a net into the sea; for they were fishermen.  And He said to them, "Follow Me, and I will make you fishers of men."  Immediately they left their nets and followed Him.  And going on from there He saw two other brothers, James the son of Zebedee, and John his brother, in the boat with Zebedee their father, mending their nets, and He called them.  Immediately, they left the boat and their father, and followed Him.
18-22. These four disciples had already met our Lord (John 1:35-42), and their brief meeting with Him seems to have had a powerful effect on their souls. In this way Christ prepared their vocation, a fully effective vocation which moved them to leave everything behind so as to follow Him and be His disciples. Standing out above their human defects (which the Gospels never conceal), we can see the exemplary generosity and promptness of the Apostles in answering God's call.
The thoughtful reader cannot fail to be struck by the delightful simplicity with which the evangelists describe the calling of these men in the midst of their daily work.
"God draws us from the shadows of our ignorance, our groping through history, and, no matter what our occupation in the world, He calls us in a loud voice, as He once called Peter and Andrew" ([St] J. Escriva, "Christ Is Passing By," 45).
"This divine and human dialogue completely changed the lives of John and Andrew, and Peter and James and so many others. It prepared their hearts to listen to the authoritative teaching which Jesus gave them beside the Sea of Galilee" ("ibid"., 108).
We should notice the words of Sacred Scripture used to describe the alacrity with which the Apostles follow our Lord. Peter and Andrew "immediately" left their nets and followed Him. Similarly, James and John "immediately" left the boats and their father and followed Him. God passes by and calls us. If we do not answer Him "immediately", He may continue on His way and we could lose sight of Him. When God passes by, He may do so rapidly; it would be sad if we were to fall behind because we wanted to follow Him while still carrying many things that are only a dead weight and a nuisance.
Source: "The Navarre Bible: Text and Commentaries". Biblical text taken from the Revised Standard Version and New Vulgate. Commentaries made by members of the Faculty of Theology of the University of Navarre, Spain. Published by Four Courts Press, Kill Lane, Blackrock, Co. Dublin, Ireland. Reprinted with permission from Four Courts Press and Scepter Publishers, the U.S. publisher.