Generalized anxiety disorder and phobic disorders are characterized by highly distressing and excessive worry and anticipation of impending danger. Apart from psychological symptoms, there are physiological symptoms, e.g. fast heart beat, fast breathing etc. Some level of anxiety is experienced by everyone every day, and everyone finds certain things particular stressful to them. 

You can refer to the following website.

What is Generalized Anxiety Disorder？

The source of information is provided by the Hospital Authority Castle Peak Hospital