Did you know that the quickest route to the amygdala (emotion regulation centre of the brain) is through the sense of smell?
One of my favourite ways to self-soothe, which is simple and easy to do, is through smelling something calming and focusing on the sensation and/or positive associations. I use scented oils because they smell overpowering and intense, which I like because it is easier to then focus on them one-mindfully. You can also get a whole range of scents to experiment with, and they each have their own unique influence on the body.
I totally had a shitty day, but at least I get to go to sleep inhaling the lavender oil (which promotes sedation and relaxation, by the way!) generously dabbed over my pillow. 👍