I wanted to riff off Weasel's OP...
Every day I come here and when I log in there are (for instance today) - 56 registered members online and 227 guests. That's a lot of lurkers. I understand lurking, especially on a site like this. It's a sensitive subject and it beats us down when we are under the influence.
I've always been chatty, and in real life your eyes might glaze over after a few hours with me, since I will talk about any subject - social anxiety has never been one of my problems - I think I suffer from the opposite. So, it's easy for me to type out my thoughts and hit, "Post Quick Reply."
I'm not particularly thin skinned, especially on forums. I mean, we aren't even real, right? I don't worry about saying the wrong thing nor do I worry about someone taking offense. (I do have a problems leaving well enough alone, though - thank you, "edit" feature.)
I've seen many posters with a few posts who say, "Don't know what to say," or something similar. I understand that. But I'd just like to say, posting is so therapeutic. This is the kindest and gentlest of forums, and the site administrators and moderators do a very good job of looking out for any problems. So if you're lurking and haven't joined in yet - this is your invitation.
tl;dr
It works if you try it. Keep reading, and welcome.