Q: When I meditate, when I do a body scan or while focusing on the breath in my lungs or nose, my attention is like a little cloud that moves through my body. It's very spacious, and I can definitely feel it moving, changing in shape and size and density - at times, I can almost "see" it. When you lose focus and drift off in thought, where does that little cloud go?
A: When you meditate, you are “going within”, and as such your attention is expanding due to a process of de-focusing. When you are in the world, your attention is focused on a particular experience, be it working on a computer, exercising, talking with someone, or something else. So, in the first case you are mindful of what is happening in your body and mind, and in the second case - you are paying attention to what is happening in the world. What happens when you “drift off in thought” is similar to that second process - your focus becomes absorbed by thought.