It depends on the current situation, location and/or state-of-mind. For instance, when I'm driving and listening to music, my mind may drift to think about relationships. When I'm in class, my mind drifts on school and sometimes work if I'm scheduled to work after school. When I don't have school or work I then think about how to plan my day. At a certain time of the day, like at 5pm, I may think about food, what to eat, how much of it, etc. There's never a day or time when I'm not thinking, i think dreaming is a form of thinking, LOL. Our minds just never rest.