Peter, Andrew, James and John were all fishermen. Not the relaxing on a lake with a single fishing road kind of fishing, but the commercial fishing – they fish to make a living.
"Follow me, and I will make you fish for people," Jesus said to them. And they laid down their nets and followed Jesus.
Jesus was asking them to cast aside the existing social order of power, privilege, exploitation, and domination, and to help usher in God's kingdom. Jesus was leading them into a new and God-honoring way of life that would bless all people.
What does it mean to 'fish for people'?
Jesus wants us to tell others about the Good News. About what He has done for us, and what He wants to do for them.
God is the One doing the calling.
We are called and chosen not because we have something extraordinary to give or to offer. We are picked because God is the One doing the calling.
"Is God really calling me?"
This question must've popped up in all our minds. God's Kingdom functions very differently from the world we now live in. The ideas and possibilities that we imagine as successful – God avoids and ignores. The ideas and possibilities for which we can only see failure – God uses those to work in the world.
Instead, God chose things the world considers foolish to shame those who think they are wise. And he chose things that are powerless to shame those who are powerful. God chose things despised by the world, things counted as nothing at all and used them to bring to nothing that the world considers important. As a result, no one can ever boast in the presence of God.
Jesus has called you and I to be fishers for people. To spread the Good News, to spread the Gospel, to glorify Him and bring many to Jesus.