I have exhaustively searched for answers to my question here and on Google. I have found some great resources and learning tools for understanding Git and what it does, but
Try keeping a bare repo on the usb stick and clone it to the machines you are working on.
Before you pack up for the day or complete to remove your stick, push your changes back to the "origin" (which is the bare repo on the stick).
When you open up on your other workstation (home?) fetch your changes.