The sea became rough because a strong wind was blowing. When they had rowed about three or four miles, they saw Jesus walking on the sea and coming near the boat, and they were terrified. But He said to them, “It is I; do not be afraid.” (John 6:16-21)
Fear is sometimes good for you. It stops you from taking unnecessary risks. From being reckless and unthoughtful in what you do. Fear is natural.