The conceptualization of health has been evolving, especially with the advent of the COVID-19 pandemic in 2019, broadening beyond a singular definition of complete well-being to incorporate individual characteristics as well as contextual factors. In this dissertation, I propose a multidimensional model of health that applies to three disparate contexts: Chinese medical residents in Wuhan, a cohort comparison of two generations in the United States, and U.S. older adults who delayed medical care during the COVID-19 pandemic. The first study examines the determinants of medical residents’ quality of life based on fieldwork conducted pre-pandemic in Wuhan, China. Psychological drives (intrinsic and extrinsic motivation), along with external support from social interactions, significantly predicted the health and happiness of these medical residents. In the second study, I used longitudinal data from the National Social Life, Health, and Aging Project (NSHAP Rounds 1-4 from 2005-2021) to compare Traditionalists’ and Baby Boomers’ partnership and sexual activity behaviors, and to examine whether sexual activity and relationship quality can predict physical and mental health, respectively. Boomer women were less likely to be partnered and more likely to be sexually active than their Traditionalist counterparts. Sexual activity was able to predict physical health five years later, whereas relationship happiness was positively associated with current mental health but not a predictor of future mental health. Finally, in the third study, I looked at the delays and completions of needed medical care during the COVID-19 pandemic in the U.S. using data from the NSHAP-COVID Study (2020/21), and found that socio-demographic disadvantage, poor emotional health, and resource deficiency in terms of financial and social capital, were strong predictors of delaying needed medical care; race/ethnicity and self-rated health predicted differences in completion of care and method of completion. In conclusion, I advocate for improvements in patient-physician trust, as well as more widespread mental healthcare and awareness, to advance global and public health systems.