It sounds like you like the familiarity of them. I'd treat them like "pets" and thank them when they show up, give them a pat or two, but not otherwise engage with them. Just go back to whatever you are doing and do that. Concentrating on what we're doing is the best way to keep focused I think. Like Muffy's son, use the thoughts to remind you to concentrate on how to solve what is making you anxious in the first place and how to get beyond that.