I was first introduced to the method at a coaching workshop run by Sue Walden from Improvworks. Sue is an inspirational speaker - if you ever get the chance to attend one of her events - don't hesitate.
You'll need someone to work with.
Ask the other person to tell you a story of their choice at a slow and measured pace and ask them to keep going for at least 2 minutes. The topic could be their potted life history, their dinner last night, their favourite film etc.
Advise them that you will be repeating everything they say out loud.
As they start their story repeat their words back to them. It will feel a bit strange but keep the same pace as them, be accurate and maintain your focus. You should be milliseconds behind them. You'll hopefully find that it's fun. You'll almost definitely find that you won't be able to focus on any of your internal dialogue (there will be no cognitive space left!).
Once the two minutes is up try and summarise the contents back to the other person. You should find it quite easy (and it gets easier the more you practice).
They try the exercise again - with a different story. But this time, just repeat the words in your head, don't say them out loud. Again try to summarise the person's story after two minutes.
And that's it!
I told you it was simple. Sue told us - that from her experience - this technique has transformed many relationships that were in great difficulty and on several occasions, saved them from destruction.
I use the technique on a daily basis - particularly in my coaching work but are many other applications. It's brilliant for focus and eliminating internal dialogue. Have a go and let me know how you get on.