This is sort of out-there, but I've noticed lately that those of us who talk too much, seldom speak in actual sentences. Instead we link sentences together with 'buts' and 'ands' and 'ors.' It keeps other people from joining the conversation, because there's nowhere to jump in.

If you can, try to push yourself to use real sentences. You will automatically speak less, and people will be better able to jump in and say 'oh, thanks for the chat but I have to go now.'