Bhagavad Gita · Chapter 14: The Three Qualities of Nature

Bhagavad Gita 14.19

nānyaṃ guṇebhyaḥ kartāraṃ yadā draṣṭānupaśyati | guṇebhyaśca paraṃ vetti madbhāvaṃ so'dhigacchati ||

When one who sees perceives no doer other than the qualities, and knows what lies beyond the qualities, that person attains my state of being.

Modern context

The goal is not to become perfectly sattvic. It is to see that all three gunas are doing the acting, and to know what lies beyond them. The witness who sees the gunas at work is not itself a guna. A person who understands this can watch their moods, energy and dullness come and go without being defined by any of them.