Yeah, so you think

Wouldn't one think that it would be an easy thing for a writer to do something they do a lot, about themselves. I mean every time I go to write anything I describe so much and in such good detail that I get the images I want to come out. So why is it so hard to describe myself? I mean every time someone asks me to describe myself I go blank. What do they want to know, what do I want them to know? Plus a million other questions run through my head making me think how to I do this, how to I describe myself. I just don't get what I should say, what I should tell them. It is all very confusing to me.