Anxiety
Anxiety is the most common mental illness out there, and it takes a lot of different forms. Experiencing some level of anxiety is a normal part of being human, but for people who have an anxiety disorder the worry or fear do not go away, and get worse over time. Some people experience generalized anxiety, where the negative thoughts and feelings are present in a variety of circumstances, while others experience social anxiety, anxiety in crowds, and sexual anxiety, just to name a few. Anxiety can cause intense and prolonged feelings of fear and distress that occur out of proportion to the threat or danger at hand. Anxiety is treatable.
Each person is unique, and should explore their options and select for themselves the most effective coping mechanisms for dealing with anxiety. That being said, many people have found successful treatment for anxiety through things like psychotherapy (often Cognitive-Behavioral Therapy), support groups, medication, spiritual and indigenous approaches to healing, and stress management and relaxation techniques.