What makes one thought obsessional and another not is the IMPORTANCE and MEANING you attach to the thought.
When you DON’T attach a great deal of importance to a thought it won’t cause you any distress. For instance, even when you are feeling anxious you will still have many ordinary day to day thoughts –
With panic disorder the thoughts might be something like..
Because the perceived MEANING and IMPORTANCE of these thoughts is frightening this activates Fight or Flight sensations.
We then try to BLOCK or AVOID the thoughts but the paradox is that the more you try to block thoughts the MORE importance you attach to them and so they increase as does your anxiety and fight or flight sensations which leads to even more thoughts.
You can also become quite fatigued. It’s like waiting for something bad to happen for hours or days at a time – it’s no wonder you can feel exhausted.