Phenomenological analyses of ageing and old age have examined themes such as alterity, finitude, and time, not seldom from the perspective of “healthy” aging. Phenomenologists have also offered detailed analyses of lived experiences of illness including lived experiences of dementia. This article offers a phenomenological account of what we label as entering the grey zone of aging between “healthy” aging and aging with a disease. This account is developed through a qualitative phenomenological philosophy analysis of elderly persons’ lived experiences of being tested for dementia through primary care in Sweden, i.e., within a cultural context where dementia commonly is understood as a frightening a loss of self even though this understanding also is questioned. To enter this grey zone of aging, we argue, does not dissolve dynamic self-becoming but can involve an experience of oneself as being old. Further, in the grey zone, the self experiences itself as neither fully healthy nor as having a disease, and as needing to negotiate and live this ambiguity. To enter this grey zone is to enter an affectively charged, sociocultural and medicalized zone, and while the self can still act in different ways within it, staying in the grey zone can result in a re-orientation in the self’s mode of being, in ways that are thoroughly beyond its control. To stay in the grey zone can have detrimental effects on the self, even though the self does not have a disease: the self can become “stuck” in a reflective mode of attending to embodiment, aging, health, and disease.