You told yourself that you would withhold information when strangers would ask you about your day.
You tell yourself that it's a social manner only used to get on with life. You tell yourself that you made a situation awkward at the gym when giving too much information on your personal history before.
Then you go ahead and do it all over again, because the customer you were ringing up asked how your day was.
This leads you to tell her about your headache you've been battling all day and that maybe it's from a lack of sleep because you were baking your sister's birthday cake all night. You tell her how awesome it will be be because she is a librarian so you made it look like a stack of books.
It's when you run her card in the machine that you realize that you told her all of this information when she didn't really need it. You tell her that she probably didn't expect a life story when she asked you how your day was.
She tells you that she works at the bank so it happens all the time. You come back with how it happens all the time in retail too, but you refrain from going on about how some people have the saddest stories and some people plum talk your ear off.
Maybe you're learning!