Stop exposing myself to stimulation and entertainment. It's easy to remove myself from work and people who stress myself out, but for introverts like me, well we need rest, not just a break from stuff other people want us to do. For me, that includes taking breaks from stuff like coffee, video games, novels and the internet, that's stimulation too. In the best of worlds I go out in the woods, light a campfire, and just stare at embers all evening until I fall asleep. Otherwise, hot bath or sauna. Those are nice.