Mowing does it for me as well. It's why I carry a pocket notebook and a pen with me. I avoid apps because distractions can pull me, like an unread text message

Mowing does it for me as well. It's why I carry a pocket notebook and a pen with me. I avoid apps because distractions can pull me, like an unread text message and I lose my flow of thought. Occasionally I even write pseudo paper that I wrote in my head while doing something else. I think you identified an important part, it's the habit of doing something, while your mind doesn't have to use a lot of horse power. I never thought about it from that perspective, but it rings true.