You do what you do for the same reason that everything else does what it does; the raw pursuit of ongoing existence. That said, with human beings, it's a bit more complicated than that. Check this quick clip out and see if doesn't strike a familiar note with you and how your own life has been rolling along. Understanding the role of Identity Survival can be especially helpful when struggling to understand how it can be that some folks can be so terrible. It's not as mysterious as it might seem to be at first glance.