•Positive and negative emotions are related to maintenance or decline of health.•Mixed emotions, reflecting one’s ability to regulate emotions, impact health.•Emotion regulation, a transdiagnostic process, also influences physical health.•Emotions affect health by altering biological function and health-related behaviors.•Emotions influence biological processes like inflammation and metabolic profiles. Both positive (e.g., happiness) and negative (e.g., anxiety) emotions have been distinctively associated with health and disease outcomes. However, whether emotion-related effects are driven by specific emotions or by shared underlying features of similar co-occurring (or mixes of) emotions is still debated. This narrative review summarizes recent scientific advances regarding whether mixed emotions and emotion regulation abilities influence physical health over the lifecourse. While behavioral and biological pathways are commonly proposed to explain these relationships, biological pathways are less well understood. As a result, here we specifically focus on known and novel biological pathways. Future directions for empirical and clinical research aimed at identifying ways to lower the risk of and burden related to chronic diseases are also discussed.