Mental Grounding
Have a good look around and describe your environment in detail: e.g. I am on the train; I can see trees and a river...
Mental games: e.g., go through the alphabet thinking of different things such as types of dogs, cities etc.
Age progression, if you have regressed you can slowly go back up e.g.: I am now 9, 10 etc. until you are back up to your current age.
Describe an everyday activity in detail, such as how to make a recipe.
Imagery, for example imagining a stop sign in your head, gliding on skates away from the pain, changing the 'TV channel' in your head to a better' show' or imagining a wall as a buffer between you and the pain.
Safety statements, thinking I am safe now, I am in the present not the past, I am in this location and the date is......
Use humor, think of something funny.
Use concentration, say the alphabet backwards or practice some tricky sums.