I think about the next two things I should be doing/saying/checking. Then I think about the next eight things after that. I think about when I will be able to get out of the seat to get to the loo.
I think about what would happen if the FMC failed. I think about what I would do if the chap on my left died right now.
I think about when I will be able to pay my bills off. Playing in the back of my mind is a song I heard on radio one at the check in that morning, maybe "Teenage dirtbag".
I think about how happy/lucky I am to be here.