This study utilized a substantial longitudinal database spanning 20 years of follow-up among individuals between 65 and 80 years old at the time of recruitment, commonly referred to as the younger old in China. There are three primary objectives for my signature work: 1) to assess the correlation between positive disposition and negative disposition with all-cause mortality; 2) to quantify the mediating effects of health-related biological and behavioral factors in elucidating these associations; and 3) to explore potential differences in these relationships based on gender.