If I'm not actively reading, I'm probably listening to an audiobook. The advent of headphones and portable media devices has been, in my opinion, the single greatest technological advance for introverts in the history of the world. It allows me to not only ignore the people around me, but also listen to some of my favorite books! It does, however, mean that I will occasionally burst out laughing at seemingly nothing, but I'm used to the strange looks by now.
The other important thing for me while on my daily commute by public transit is to have something to do with my hands. If I'm reading, well, that takes care of things; however, many mornings I'd rather do something else, while listening to a book. And lo, the power of crochet kicks in.
I spend a fair amount of time making things for people other than myself, mostly because I will actually finish something I'm making for someone else. I may still have a blanket that I started working on when my husband and I were first dating...twelve years ago. It's maybe a third of the way done.
At any rate, the combination of a good book on audio and something useful for my hands to be doing makes that first and last part of the work day something that helps me deal with the anxiety levels. There are days, of course, when just leaving the house is too much for me, but on those borderline days, being able to focus on the world of a book and the yarn and hook in my hands is enough.