All fear is, in essence, fear of the future.
We are afraid of the things that have not yet happened, but which if they did might bring us pain, suffering or some other discomfort - or stand in the way of some future contentment. And we are afraid that circumstances that are already causing us displeasure may continue in the future. We may fear losing our jobs and the resulting drop in living standards. We may fear failure for the disapproval it might bring. We may fear having nothing to do because we might get bored.