The aim of this study is to investigate the psychological mechanisms that impact the academic achievement of lifelong education college students. To achieve this goal, we classified the cluster type of grit based on the subscales of the Korean Grit Scale, namely effort-sustainability, passion-pleasure, and passion-meaning, and examined whether there were differences in academic achievement among the cluster types. We also investigated whether academic achievement varied depending on the cluster type and level of job stress. Cluster analysis, multivariate analysis, and intervention effect analysis were performed on a sample of 238 lifelong education college students by measuring grit, GPA from the previous semester, and job stress levels. Results showed four clusters: “low grit group”, “passion (pleasure) group”, “normal grit group”, and “high grit group”.
Furthermore, there was a significant difference in academic achievement depending on the cluster type, with the high grit group demonstrating higher academic achievement and lower job stress compared to the low grit group. Additionally, in situations of high job stress, the passion (pleasure) group showed higher academic achievement than the low-level grit group. Moreover, in situations where job stress was moderate or high, the average level grit group demonstrated higher academic achievement than the low-level grit group. Based on the study’s findings, we discussed the implications and suggested further research.