Silence

Whatever comes, will, instantly or eventually, go. Have no doubt about that.

You can read Nididhyāsanā texts as much as you want. But because it came, it will go. The verbal insights from the Upaniṣads came to you; hence will go. The Supreme Bliss felt after contemplating a verse from the Ashtavakra gitā came and will also go. Likewise, people, thoughts, circumstances, feelings, techniques, pointers, all came so will go. 

However, there's something always here: Silence, Stillness, Peace. 

This is not one of those "do's and don'ts" instructions. Someone attached to smoking versus someone attached to not smoking is the same. Go about life like a dry leaf, blown by the wind of prārabdha. 

(Saying the following implies a doer because it isn't possible to get the message across otherwise)

The only "aim" is to (be in touch with/abide/rest in) Silence, at all times now.