It is where you stop and decide if this is a mental or physical experience. Then you ground yourself. What am I touching, seeing, hearing, etc. I definitely suggest the book The Happiness Trap. It helps to get thru an experience, rather than avoiding it. I can't even tell you how many times it has helped me get thru what could have been a full blown panic attack and how many times I've used it to stay sober. I'm dedicated to ACT therapy. CBT never helped me much.