Talk to your boss and see if there isn't some other job
you could be doing, or studying for. You could do some
of the office cleaning, or painting, or making a hand made
quilt for the boss' wife or mother.
You said you wanted to use your brain, look around you
and see what is there that you could change, and talk
to your boss. Perhaps because you are like family, he
doesn't want to work you too hard.