Feeling unsure is a universal experience of health and quality of life. The purposes of this research study were to discover the structure of the lived experience of feeling unsure, to add to the body of knowledge on the phenomenon of feeling unsure, and expand the humanbecoming school of thought. The Parse research method was used to guide this study and answer the question, What is the structure of the lived experience of feeling unsure? Participants were 10 individuals living with chronic heart failure in the community. The processes of dialogical engagement, extraction-synthesis, and heuristic interpretation were used. The central finding of this study was the following structure: The lived experience of feeling unsure is discomforting trepidation with unassuredness-assuredness, as vigilantly anticipating possibles with treasured alliances arises with moments of acquiescence. New knowledge extended the theory of humanbecoming and enhanced understanding of the experience of feeling unsure.