Feeling anxious? Do something. Move.
First, try working directly on the problem. Make some telephone calls, draft that e-mail, confront that person.
Nothing you can do about the problem right now? Write it down in a journal. Nothing formal, just a pencil and a scrap of paper.
Or take a walk around the block. Read a book or listen to an audio book. Or work on your hobby. Take up a new hobby if necessary.
Or sit quietly and ask for help. Then drop it.
If you are anxious, you probably are going over and over the same mental ground.
Do something. Break the cycle.