“If we still cling to something we will not let go, we ask God to help us be willing.” (Page 76, Big Book)
To not let go of something is to continue to think about it when there is no constructive purpose in doing so.
Method:
Ask God: ‘Help me be willing to let go of this’. Be prepared to look at it differently. Imagine or visualise God looking after the matter at hand. Treat the problem as already solved. Direct attention elsewhere.