Breathing, digesting breakfast, sipping tea, worrying about the time so I can get to work on, thinking, typing, utilizing my optic sensors, typing (keyboarding for all you Digital Natives), and all this while phagocytes and other nice cells search out and destroy other nasty cells. My lungs are adding oxygen to the hemoglobin in my red cells so that they can carry it to my bodily extemities, my heart is pumping away, neurons and synapses are functioning, intestinal ciliae and muscles are carrying food from my stomach to my intestines (see #2, above), and my body is converting glucose to heat (it's 47 F outside).

But I'm not multitasking on the computer. I'm kind of an old-fashioned sort of guy, I guess.