I've been considering the question "What are you thinking?" as a mindfulness query. Usually I ask someone this out of curiosity or wanting to connect, so they'll share their internal world.
Maybe the question should be: How are you thinking? — to bring awareness to thinking. Notice that you're thinking. Notice the contents of the thoughts, without getting caught up in the story. Feel how thinking affects the body.
Mindfulness of thoughts is one of my favorite formal meditation practices lately. I get a kick out of it, which is good because there's a lot of thinking happening over here!
I enjoy watching the impulsiveness of thoughts, and how much they're chomping at the bit to spring me into action. Maybe I enjoy it because there's more freedom in watching thoughts rather than being so driven by them.
I love sitting practice, because of the relief of knowing that during this time I can't do anything else. All these thoughts, coming and going, don't matter. There's nothing else to do. Because all I'm actually doing is sitting here with awareness.
It's so great to just let the thoughts think and not have to do anything about them. So, how are you thinking?