"Non-doing" is a woo name for relaxing doing any "mental moves" (eventually also relaxing efforts to relax mental moves, recursively).

The most common mental doings are trying to prolong feeling good, shorten feeling bad, and excluding parts of experience from awareness.

Non-doing includes not manipulating experience into blissful states like Jhanas or away from states such as fear, anger, sorrow.

Non-doing does "attain" a sort-of-state, "non-bliss", the bliss of no existential anxiety about any situation continuing, ending, or transforming.

Non-bliss is, for many who become familiar with it, fundamentally, a more attractive sort-of-state (sort-of-state, because it is the allowance of all states) than any particular state.

Non-bliss could be described as the fruitional state of searchlessness. Of course, standard spiritual frameworks don't work that well here, but we work with the language as best we can.