Summary: Jesus takes his disciples from shallower faith to deeper faith.
Jesus, as he always does, takes the physical things, which are our first interest, and turns it into a matter of spiritual interest. And when we have learned that lesson, then God has accomplished his purpose in us and will be ready to use us spiritually.
God took fishermen and made them into fishers of men, like he did with Peter and his friends. Likewise, whatever careers we do, God will also teach us faith lessons. That is the movement from shallower water into deeper water. I am not saying that they all gave up their jobs and became full-time Christian workers. But at least there should be the transformation into a deeper spiritual understanding of life.
Gin this way, God will take doctors and make them also healers of souls, like he did with Luke. He will take lawyers and make them judges of truth, like he did with the Apostle Paul. He will take shepherds and make them shepherds of people, like he did with David. He will take builders and make them builders of nations, like he did with Solomon. He will take artists and make them communicators of beauty, like he did with Bezalel. He will take students and make them students of his word, like he did with Daniel. He will take administrators and make them administrators of his grace, like Moses or Joseph in the OT. He will take farmers and make them sowers of truth, like he did with Amos.
What is the conclusion? Don't be afraid when God is taking you from one place to another. He has a purpose. And we don't need to be afraid. Amen.