I find waiting for things physically exhausting. Waiting in lines, waiting sitting in a room, waiting on friends to decide what they want to eat, walking really slowly with an elderly relative: I find it all physically exhausting even though very little physical energy is required.
Have you ever tried meditation? Great for waiting.
I did regular meditation for a year and a half or so (now more intermittent) but never mastered the kind you can do with your eyes open. I do enjoy a walking meditation though.