"In the animal kingdom, the rule is, eat or be eaten; in the human kingdom, define or be defined."
A vita represents you in the professional world. It sums you up, and is your advocate. Like it or not, it speaks for you, and may as well do so eloquently. And curiously enough, it helps you yourself remember what you've done.
A vita need not be, and often isn't, simply one document. Depending on your intentions for it, you may want to frame your information in a variety of ways. The information, of course, will not change--but how you prioritize that information can sometimes differ drastically. The vita you send, for example, to a Research I university quite reasonably will be different from the vita you send to a small liberal arts college or a community college. The key is, understand what you are doing and send the appropriate vita.
Indeed, a good, a very good vita will be some trouble to assemble, and even more to maintain. This is a good problem. Its solution will distinguish you.
"Opportunity is missed by most people because it is dressed in overalls and looks like work."
--Thomas Alva Edison