Reading and, strangely, painting are huge stress relievers for me. Then of course, so is using a vacuum or mowing/bush-hogging. Anything where I know I will see an immediate effect/have a visual that something was accomplished. Painting (anything except walls with a roller), but especially on canvas just takes me away somewhere else. Reading? A book a day person for many years now. Not sure why reading relaxes me and visual stuff like movies/videos do not.
Deep breathing/counting relaxes me the most when I remember to do it – and if I remember to catch myself and stop before I fall asleep.
Learning to drop a curtain when needed between your feelings/emotions and what you are currently doing/seeing is a good skill to have as a prepper I think.