I have to go with "basic building blocks of thought" because I am almost always counting. I do it without even noticing it most of the time, and sometimes I count in cycles, like to 5 or 10 over and over. Usually I don't remember the total of whatever I count (steps I take, for instance) but I have had periods of time when it's been really important that things work out to multiples of 5 and the incessant counting has really gotten in the way of my life (OCD much?) but by and large it's just something I have going on in my head and I don't notice it much. It can actually be sort of calming and meditative.
in reply to When I count, I think of numbers as...