Stress is a natural response to uncertainty. When we are exposed to an unknown situation, such as the prospect of our future, our brain is naturally fearful. This feeling has another name, it's called anticipatory anxiety. It happens because our thoughts are focused on a possible future or a negative outcome that we don't feel prepared for. If you find yourself agonizing about the horrible, unknown things that might happen, this is an indicator that you're experiencing anticipatory Anxiety.