While sociocultural scholars have proposed the concept of ‘fitness culture’ to represent sociocultural fitness norms (e.g., “no pain, no gain” rhetoric), the psychological endorsement of these norms have yet to be operationalized or explored. Drawing on the disordered eating literature, internalization and endorsement of normative fitness culture may contribute to maladaptive body, eating, and exercise attitudes and behaviours. As such, the purpose of the present study was to (i) characterize the endorsement of fitness culture norms, and (ii) explore the experiences of women who endorse these norms. Thirty self-identified women aged 18-35 (Mage= 25.4) were guided through a one-on-one semi-structured interview about their relationship to fitness that lasted approximately 1-2 hours. Using reflexive thematic analysis, the concept of endorsing fitness culture norms was defined as internalizing and upholding values of individualistic discipline, achievement orientation and hegemonic masculinity when engaging in fitness pursuits. The endorsement of fitness culture norms was associated with maladaptive eating and exercise behaviours, feelings of guilt and distress, internalization of the fit-ideal, and experiences of cognitive dissonance in relation to fitness-related beliefs and behaviours. Based on these accounts, endorsement of fitness culture norms seem to present a unique threat to women’s psychosocial health, and may have important implications for women’s psychological experiences with exercise.