To identify the factors that disrupt and maintain habit performance, two field experiments tested the conditions under which people eat out of habit, leading them to resist motivational influences. Habitual popcorn eaters at a cinema were minimally influenced by their hunger or how much they liked the food, and they ate equal amounts of stale and fresh popcorn. Yet, mechanisms of automaticity influenced habit performance: Participants ate out of habit, regardless of freshness, only when currently in the context associated with past performance (i.e., a cinema; Study 1) and only when eating in a way that allowed them to automatically execute the response cued by that context (i.e., eating with their dominant hand; Study 2). Across all conditions, participants with weaker cinema-popcorn-eating habits ate because of motivations such as liking for the popcorn. The findings reveal how habits resist conflicting motives and provide insight into promising mechanisms of habit change.