In a perfect environment, there would be no need for fear. In Eden, there was only one feat that Adam and Eve could have needed--and they didn't have enough of it: the fear of displeasing God--until they were already in the soup. The result was being sent out into a world full of risks and dangers. To live in this world, we were created with the potential to fear. The problem is not the existence of fears in our life; the problem is the proper evaluation of our fears.
A life without fear is a life without the opportunity to learn to deal with danger. We tend to think that protecting ourselves and our children is wise, which it is--to a point. Too much protection can be self-defeating; "helicopter parents" who hover over and run interference for their children run the risk of raising a child who doesn't do well in a crisis, because he has learned how to fear, but not how to overcome it.
It is fitting that Jesus told his followers that if they are in the right relationship with God, they only need one fear: the one that Adam didn't understand. Yes, we have other fears; we also have a proper companion for fear: courage. Courage is not fearlessness; courage is acting on a recognition that in the situation in question, fear is less important than the goal facing us.
God's plan may very likely put us in a potentially dangerous situation. When Joshua was facing the invasion of a land full of iolatrrous and dangerous people, God told him not once but three times: "Be strong, and of good courage;fear not, nor be afraid...for the Lord your God is with you wherever you go." There was, however, another side to this coin: "..that you may observe all the Moses taught you". Again, there is one appropriate fear: the consequences of not doing what they were commanded to do.
Life in this world has its dangers. There may be times that we overthink the danger. There may be times that we not adequately understand the danger. St Paul, as he faced the calling God had for him, Much of it was not easy; but he was a living example of courage. This is his conclusion: I can do all things through Christ who strengthens me. (Phil 4:13) Even the pagan Romans understood that a man of courage is also a man of faith. (Cicero).
Paul's courage extended much further than just his own survival. It has been said that there are times that standing against evil is more important than success in defeating it; the greatest heroes stand their ground because it is right, whether or not they themselves survive.