Anything in excess can be bad. Fear can help you survive, fear of failure can keep you in line to be more successful, fear shows the way to true courage, for there is no courage with overcoming fear.
Worry is concern in excess. Jesus said "don't worry about tomorrow, the evil of today is sufficient there of"
but we are to be concerned about tomorrow. Esau was not concerned about tomorrow and sold his birthright for a bowl of stew. God say "let there never be a man as immoral as esau" because he could not discipline himself, or plan for tomorrow.
all things in moderation