Noticing effort should result in a mental impression of the effort being applied, i.e. a force being applied towards the object in awareness. There is “no one” applying this effort. Rather, the effort is an internal habit which has been learned, and which can be dropped. Simply noticing the effort should cause it to spontaneously vanish, and for stillness, silence, bliss and equanimity to rush in in its place. Effort is dropped simply by noticing it is being applied.
(This glossary item is a hidden answer to a question asked in the following post: Meditation Pro-Tips Vol. 1)