I've been reading The Essential Drucker lately, and there's a story he tells that I find very insightful. I'll let him tell it:
The head of one of the large management consulting firms always starts an assignment with a new client by spending a few days visiting the senior executives of the client organization one by one. After he has chatted with them about the assignment and the client organization, its history and its people, he asks (though rarely, of course, in these words):"And what do you do that justifies your being on the pay-roll?"The great majority, he reports, answer: "I run the accounting department," or "I am in charge of the sales force." Indeed, not uncommonly the answer is, "I have 850 people working under me."
Only a few say, "It's my job to give our managers the information they need to make the right decisions," or "I am responsible for finding out what products the customer will want tomorrow," or "I have to think through and prepare the decisions the president will have to face tomorrow."
What you do and what you are responsible for doing are two different things. You are ultimately judged by your results - your ability to do the job.
This distinction applies to all aspects of life. In your own life, there are probably lots of things you are responsible for. As a dad, you are responsible for making sure your child is safe, loved, stimulated, and disciplined.
As a husband, you are responsible for making sure your wife feels respected, cherished, heard, and prioritized in your life.
As an entrepreneur, you are responsible for many things, not least of which is making sure your customers are able to do what your business promised them that they'd be able to do.
Don't simply ask yourself, "What am I?" or "What do I do?" Ask yourself: "What am I responsible for?" This tells you that there is always work to be done, somewhere you can contribute.