Have you ever read this verse and got caught up on what its trying to say? It used to be a problem for me all the time. I would read it and get sucked in by the part about being a fisher for men.
While being a fisher for men may be a noble title, what Jesus is asking us to do is to follow him. If we successfully follow him, the result will become that we are fishers for men.
What exactly is involved with following Jesus? Many people have given a diverse range of opinions. What the text seems to say though is that if we follow Jesus we will become focused on forgiving people for their sins, not condemning them. It will become our responsibility for feeding the hungry, taking the friendless into our homes, visiting the sick and those imprisoned. To follow Jesus, we need to learn to love our neighbor. No matter what.
If we can become successful at doing these things, we will become a net that draws others into it, effectively making us fishers of men.