For me I try to stay as warm as possible. When it is really cold I do anything I can to stay warm. Disposable heat packs make all the difference in the world. Mentally I just let my mind wander where it wants and after awhile time just flies by. I never check my watch more than a couple of times a day. Let natural time take over and you won't notice that the day passes by.
For those of you who read while on stand, do you ever miss deer moving in the distance? I like to allow all of my senses to do the hunting so I never have packed a book along with me. Let me know how it works out for you because I love to read but have always been afraid I would miss something.