These exercises were tools I was taught by a therapist to deal with hyper-fixation/obsessive thoughts and anxiety. If these problems are causing you to be unable to function in your life please seek the help of a mental health professional. This is not intended to be a substitute for professional help.

These are two visualization exercises that help me in moments of hyperfocus/obsessive thoughts (The Rock) or in moments of anxiety (Unwinding Anxiety). I have linked multiple other common exercises in the resources section for you to try as well.
Both exercises start by closing your eyes (if you are in a safe space to do so) and taking a few deep breaths.
The Rock
You are in a large field that is littered with rocks. The rocks are different shapes and sizes and colors and are scattered around the field for as far as you can see. They are all labeled with different thoughts and memories.
You are standing in front of the largest rock in the field. That Rock is labeled with whatever your current obsessive thought or memory is.
Every time you think about the trauma you are trying to lift this boulder and carry it around. When you try not to think about it, the boulder begins to crush you from its weight, so you return to thinking about it, to keep yourself safe.
In this exercise, we are going to learn how to slowly set down the rock. You may not be able to set it down all the way on your first try, but continue the exercise to the end so you can practice for the next time you need help setting the rock down.
Now, I want you to visualize yourself holding this boulder above your head. Take some deep breaths and slowly put it on the ground.
Breathe in. Breathe out.
Your arms are still around the rock, but it’s no longer going to crush you. Take a few more deep breaths and relax your shoulders. Your grip on the boulder should also relax.
Breathe in. Clench your hands into fists. Breathe out. Open your palms and turn them up in your lap or by your side.
In your mind, take a step backward, so that your hands are still in contact with the rock, but the rest of your body is no longer touching it.
Breathe in. Breathe out.
Visualize the boulder shrinking with each breath out.
Breathe in. Breathe out. The rock slowly shrinks a little more.
You are now only touching it with one hand, then just your fingertips.
Breathe in. Breathe out.
One finger lifts, then another, then another. Soon, you are no longer touching the rock, but you are standing back merely observing.
Breathe in. Breathe out.
The longer you observe, the smaller the rock becomes.
As the rock shrinks you notice there are also flowers in the field. You feel the sun on your face and can smell the scent of spring in the breeze.
Breathe in. Breathe out.
Keep breathing until you no longer notice the rock, but instead see the rest of the field.
Unwinding Anxiety
This exercise is to calm anxiety when you are feeling the physical effects in your body. For me, anxiety sits in my chest, right at the base of my throat. This area gets very tight and I have a hard time breathing.
I close my eyes and thinking about the direction the area is tightening. Is it tightening clockwise, or counter-clockwise? Sometimes placing your hand on your chest can help you slow down and thinking about the direction the tightening is moving.
Breath in deeply to the count of 5, hold your breath for two counts, slowing the spiral of tightening. Then breathe out to the count of 5, unwinding the tightening of your chest as you exhale.
Repeat until you feel calm.