I find myself stuck in a thought and having fussy feeling in my head sometimes. It is easy to identify these moods but to get rid of these are lot harder. I put things on paper and came out with a list of actions you can take to make some space in your head.
Cleaning up: Letting go for a while and just tidying your desk or room you are working has magical power to gain some space to new thoughts
Sleeping: Event the shortest nap to a good night sleep execute of your brains garbage collection. When you wake up, things appear to be simpler you thought
Lists: Lists can be used many ways. You can empty your should's and could's spinning around in your head and you can use lists to make sure you are doing things right and packing all the necessary items to your trip
Visualizations: Visual presentation could give you another perspective to your thoughts. These could be simple drawings to mind maps and posters on your wall.
When you are stuck in a thought or having low energy levels, these things could be forget easily. These actions are also counter intuitive when you are in a hurry. What you need to to is to create some trigger when you are too stuck in your thoughts.
Things that are not working: Mindless browsing, just sitting and not moving, caffeine and all the other things you can find from the modern office