My husband, an introvert with autism, wanted to chime in and say that he needs some alone time with his special interest (either baseball cards or geography/maps) to fully recharge.
Another thing that helps me is taking a shower. Simple yet effective.
I'm not a programmer, but I've taken beginner classes. I have definitely felt very Zen when I reached a state of flow doing homework with very basic programming.
For me nature. I love being surrounded by nature. Sometimes I just chill on a bench with a coffe or listen to a podcast in a park, while watching the clouds pass by or watching people walk their dogs.
It sounds boring, but really helps to focus my thoughts again.