Imagine creating your own hell. Eternal nothingness, suffering, angst, repeated in a loop for all time.
The possibilities of your mind are endless. You can wander off onto limitless adventures, creating a secondary self of yourself to fly in your imagination.
With enough help, you can practically create your own pinnacle of suffering within that imaginary dimension, manage to get yourself stuck in it and suffer for all eternity.
The same memory, the same thought, the same pain, repeated in cycles, time and time again.