It's like you're doing meditation, and thinking "I shouldn't be thinking". But you can't be conscious about being unconscious. Or something like that.
Which is a weird thing that happened to me or that I became aware of a few years ago, late at night or when I lie down for a nap I can get into that state, it's like dreaming while being awake. Of course, as soon as I'm aware of that I snap out of it, it's like "hey I want to keep following that train of thought" but it doesn't work when it's active.
Of course, if I don't snap out of it like that I will invariably fall asleep, lol.