It's hard because people often don't recognise shyness; they think it's just someone being rude. I have had to work to overcome that, especially if I'm meeting my readers at author events, because I don't want them to think I'm snooty or rude.
I'm extremely introverted. I used to think it was shyness, but I got over that, so it must be door No. 2. It's still hard for me to be away from home much, and I have to make sure I get lots of time alone in my room when I'm touring.