According to Wikipedia, anxiety is a negatively colored emotion that expresses a feeling of uncertainty, the expectation of negative events, and hard-to-define premonitions. Anxiety is associated with the subconscious mobilization of the body's mental forces to overcome a potentially dangerous situation.
Why does anxiety make us so uncomfortable? There are two problems here. First, the causes of anxiety, unlike fear, are often not recognized by us or are not fully realized. Secondly, as a rule, the mobilization of the forces of the body is meaningless, since it rarely helps to resolve the situation that causes anxiety, "here and now." Thus, our internal tension does not find a natural outlet, and the brain, trying to get rid of it, finds senseless and often harmful activities for us - nail biting, smoking, snapping the knuckles, picking something on the skin and much more. . That is, we are doing something, the tension seems to be decreasing, but the anxiety has remained the same, only with bitten nails.