It depends on the time of day. If it is morning I think about all the things I need to do and plan them in my mind.
If it is night time I think about all the things I accomplished that day and pat myself in the back.
I normally think - this water is too cold. Now its too hot. I guess I just plan my day out in the morning then in the evening shower, just random things ranging from football to women to cars to women again!