Affect has long been of interest in early childhood education, where social and emotional dynamics are seen as critical dimensions of learning, intricately linked to embodied activity. As part of the special issue Centering Affect and Emotion Toward Justice and Dignity in Science Education, this paper conceptualizes affect through children's bodily comfort. Data were collected in two Kindergarten classrooms participating in an integrated computer science-STEM curriculum that involved small groups of children engaging in floor-based activities. Focusing on body positioning, we use interaction analysis to explore how a focal child found a comfortable fit in her learning environment, highlighting the role of clothing in establishing a mundane sense of comfort. We found that fitting in the space and fitting in with others involved creating comfortable spaces, or comfort zones, in the classroom. For focal participant Theresa, a comfort zone involved physically positioning her body and negotiating norms of social comportment that govern how different bodies come to feel like some-body. We discuss ways in which some children perform extra physical and emotional labor to establish comfort zones in the classroom, and how this contributes to their felt sense of belonging and dignity, whereby all children are valued participants and feel that they fit. We conclude with pedagogical implications of creating spaces for embodied belonging, where children feel a goodness of fit in STEM.