We all do it, especially when we are stressed or worried. Mental health issues like depression, anxiety, loss, social anxiety, obsessive compulsive disorder, borderline personality disorder, attachment disorder etc often have overthinking as a symptom.
What we are saying is stress can lead to depression and/or anxiety, particularly if the stress being felt is prolonged, unmanaged and you can’t access support. It can affect your work life and your home life.
I have worked with many people who don’t even realise that this internal dialogue is there, they accept it as who they are, not ever questioning that self-belief. But here is some things we know about failure.