@BlueBay, yeah it takes a while to get to the point of being able to catch your own thinking, but it is doable. (Sometimes if not all the time). If you practice having a higher self - someone one who is the bigger you who looks after your wellbeing, you can practice prompting yourself to check in with your thinking. What am I thinking now? Is it helpful? Yes - continue. No - drop it and substitute the thought with a strong substitute.
My strong substitute is coming into the present with conscious thought. I actually do this physical action where I point with both hands suddenly into NOW/HERE. A movement that primes my brain to switch into the present. (Looks do lally tat but works)
Seeing/looking - "what is in front of me, naming the objects - there is the bookshelf, there is the framed painting, their is the television, there is the pattern on the rug.
Hearing/listeining: hearing really brings us into the now) - what can I hear? There is a car reving, there is some magpies warbling, there is a plane far off.
Physical sense/feeling. What we can feel, there is the feel of my top on my skin, there is the too tight heel on my shoe. There is the tast of my coffee, there is the drag of my cigarette.
They are all coming into the present/now with purpose and it is a huge distraction for the broken record of self hatred. Doesn;t take long to do it, just needs to be long enough to jump the groove of the self-hate monologue. Then get on with something else.