It's something the NHS are using more for depression and anxiety - it needs to be taught by someone trained in it - but it's about being interested in your thoughts without judging them - a kind of "hmm that's interesting that I'm thinking that" and trying to accept your thoughts without being taken over ny them. I guess with all therapies / medicatiosn not everything works for everyone, but maybe it is something to dicusss with your CPN - I have found it useful at times when I can motivated myself to do it.