The act of clearing your mind
It was good.
This is a good thing to practice when you're not stressed. Then when you're in a mildly stressful situation, you can pull it out of your "coping mechanisms" bag of tricks. I use this a lot while waiting in doctor offices. I like to challenge myself to see how soon I can tune out all the ambient noise and how long I can maintain it without thinking about how annoyed I am by how long I'm waitin.