Self-possessed in a sentence as an adjective

Friends will respect you more if you are self-possessed enough to put your academic priorities first.

Self-possessed definitions

adjective

in full control of your faculties; "the witness remained collected throughout the cross-examination"; "perfectly poised and sure of himself"; "more self-contained and more dependable than many of the early frontiersmen"; "strong and self-possessed in the face of trouble"

See also: collected equanimous poised self-collected self-contained