Apprehensive
A person who is preoccupied with the thought of something that the person is not able control is being apprehensive. One who worries excessively, can be called apprehensive and he or she might be suffering from anxiety disorders. A tendency of a person to be apprehensive might be understood as a type of mental health condition. If one exhibit such behaviour, besides other symptoms, he or she might be suffering from an anxiety disorder, he or she might respond to any ambivalent stimuli and situations with fear and dread. He or she might also experience physical signs of anxiety, which include pounding heart and sweating.
It’s quite normal to feel apprehensive sometimes. One might feel anxious or nervous if he or she has to tackle a problem at work, take a test, go to an interview, or make an important decision. Some level of apprehension is beneficial and enhances performance. For instance, worry or apprehension often assist an organism to notice dangerous situations and focuses their attention towards the danger, so he or she can avoid the threat and stay safe.