Learning to shut out the noise

Things have been going well recently. Since I've not been so preoccupied I've managed to get into my work and feel as thought I'm living a fairly normal life and enjoying it all. But over the last couple of days I've been a bit cloudy of mind. It happens occasionally where I cannot think clearly as my mind is a bit sluggish. I'm not sure why. I guess it happens to us all. Anyway, it makes my self-esteem plummet and I become very self-critical. I end up thinking I'm stupid and am not very kind to myself. All this critical self talk escalates to thinking of other people telling me I'm no good and patronising me. My imagination can be quite vicious. Does this make me sound crazy? I have had thoughts like this on and off for a long time usually when my self-esteem is low. I am sure everyone thinks like this sometimes  as we all have insecurities and we all have an imagination! I just wonder if  the amount I do it is damaging to me. I need to stop thinking like that but it is hard.

I've tried not to be preoccupied with it and have been trying to throw myself into my work and think of external things rather than obsess about the noise going on in my head. Amazingly I have found I have been able to push aside my mind troubles and focus on work more easily than before. For me this is really pleasing as I used to be at the mercy of my obsession with my problems and I always envied those who can just shut things off and get on with their tasks. Now I can do that too. I think it will be an effort to maintain though as I'm sure it is a phase which might change back.