This paper stems from research and practice conducted to interrogate how best to design for flourishing health and well-being in architecture, grounded in the neo-Aristotelian philosophical concept of eudaemonia (i.e., being one’s best self) (Deci & Ryan, 2008). Initially explored as a theoretical construct (Mikus & Grant-Smith, 2021), Eudaemonic Design (ED) or designing for eudaemonia in the built environment, was explored through pragmatic empirical research (Mikus, 2023) to evaluate its application in spatial design practice. The ED approach seeks to foster eudaemonic well-being (Ryan & Deci, 2001) and optimal physical, mental, and social health for occupants of a space to be(come) their intrinsically motivated best selves. Recognized as foundational for promoting flourishing health and well-being in the built environment and in the humans who inhabit those spaces (Mikus & Grant-Smith, 2021), the research explored what an optimal, health-supportive home might look and feel like to support ageing in place, proposing design principles that could support that end goal. Balancing best practice and the need to adopt remote data collection, creative methods (e.g., cultural probes, Mirofacilitated workshops) were deployed virtually with older adults and designers to envision and design for their future older adult selves. This approach bridged the divide between designedfor and designed-by groups, precipitating mutual inspiration, transformative change, and meaningful eudaemonic well-being impact. Conducted with and for older adults, building on their lived experiences, this work aligns with Design for All or Inclusive Design theory (Mikus & Rieger, 2021), suggesting broader applicability for productive use with other demographics (DOGA, 2018; Light et al., 2015; Mikus, 2021). Through Research Through Co-design (Busciantella-Ricci & Scataglini, 2020), nine ED principles were developed, each forming a continuum between dimensions of a core theme, supporting adaptable eudaemonic environments that align with individual preferences and the contours of a eudaemonic life.