A monk came to say good bye to Ch'an master Niaowo (Bird's Nest). He said:
-Thank you, Sir, for everything you've done for me. Now I got to go.
-Where will you go?
-Any place where I can learn Buddha dharmas.
The things to watch are comparative judgments, thoughts and worries. I don't think you need to watch any in the physical world of form. I'm looking at a computer right now but it's basically empty until I employ the keyboard. Observing doesn't effect any object. If you watch from within the activity of the mind does the work of Buddha.