"If you find yourself awake in the middle of night worrying, with thoughts whirling round repeatedly in your head, he has several strategies you can try. This is where imagery comes in useful again. Imagine there’s a box under your bed. This is your worry box. As soon as you spot thoughts that are worries, imagine taking those individual worries, putting them into the box and closing the lid. They are then to remain in the box under the bed until you decide to get them out again. If the worries recur, remind yourself that they are in the box and won’t be attended to until later on. An alternative is to choose a colour and then picture a cloud of that color. Put your worries into the cloud and let it swirl backwards and forwards above your head. Then watch it slowly float up and away, taking the worrying thoughts with it."
"Likewise, telling people not to think of their worries isn’t going to work. Instead Kerkhof recommends the opposite. Set aside 15 minutes in the morning and 15 minutes in the evening to do nothing but worry about the future. Sit at a table, make a list of all your problems and then think about them. But as soon as the time is up you must stop worrying, and whenever those worries come back into your head remind yourself that you can’t contemplate them again until your next worry time. You have given yourself permission to postpone your worrying until the time of your choice. Remarkably, it can work. It puts you in control."
from: Claudia Hammond - Time wrapped