The three gunas are applied in Indian thought well beyond metaphysics, most concretely in diet: the Bhagavad Gita's seventeenth chapter classifies food itself as sattvic, rajasic or tamasic, with sattvic food described as wholesome, mild and life giving, favoured by those seeking clarity and calm. The same threefold grid extends to speech, giving, austerity and action, so that a gift given without expectation of return is called sattvic while one given reluctantly or for show is not, making the gunas a working ethical vocabulary and not only a cosmological one.
No person or substance is held to embody a single guna purely; all three are always present together in shifting proportion, and spiritual practice across several Indian schools aims to increase sattva relative to the other two as a stage on the way, since even sattva, being a quality of manifest nature, is ultimately something to be transcended rather than the final goal. That transcendence is called gunatita, being beyond the gunas altogether, a state the Gita associates with liberation itself.
Modern popular writing sometimes reduces the gunas to a simple mood chart or personality quiz, a simplification that drops both the doctrine of constant mixture and the aim of transcending sattva along with the other two, rather than resting in it as a final state.