Anxiety

It is quite common for people to experience some anxiety in life, this is quite normal.  However, how often and how severe that anxiety is can vary dramatically from person to person.  When it interferes with how you live your life, then it becomes a problem.  Anxiety can be affected by events that have happened in your life, similar events, people, or memories can trigger the 'fight, flight or freeze' response.  This response is a survival response that we all have. To begin with, your thoughts affect your emotions; both of which affect how you physically feel.  What can happen is that our thoughts, emotions and bodies can 'hold' this response called hypervigilance; where your mind and body become stuck in this mode, making it difficult to relax, being constantly on guard.  This can affect what you do or don't do. In this way your behavior backs up your original thoughts and this becomes a vicious cycle.  

Whilst it is not the same for everyone, anxiety and depression can be linked for many people.