I force myself to look at something very small or specific near me and describe it in great detail, talking out loud to myself. especially good if it involves something like counting or calculating and I can make it as complicated as possible to distract myself
like: the floor is white. it is made of shiny ceramic tiles. there are 10 tiles across and 15 down (count them) … you get the idea … that sort of shit …
really tough coz it is much more easy and comfortable somehow to be pulled back into the flashback LOL, you have to fight it