Female students, Latinx students, first-generation students, and transfer students often feel uncomfortable in science, technology, engineering, and mathematics (STEM) environments. However, some departments have been making progress in changing that. Guided by double consciousness and person-environment fit theory, we investigated the lived experiences of historically marginalized undergraduate and masters-level physics students at a large state university to understand how this particular department provides an environment encouraging all students they fit in physics. Graduated students and faculty were interviewed from California State University, Long Beach. Through the interviews, we gained an understanding of significant student experiences and their perceptions of fit in this physics environment. Department community members perceived the department environment to be open, which contributed to broadening fit and supporting diverse students to thrive. The importance of faculty agency in creating a welcoming and supportive physics environment is highlighted. Finally, we found students in this department take with them an approach to physics that they see applicable to other areas of study and their lives. We called this a physics state of mind. We include suggestions for other STEM departments based on the findings and previous research.