**5. Conclusions**

This study extended extant research by probing into whether there is a reciprocal relation between conscientiousness and well-being (subjective and physical well-being) using a two-wave cross-lagged design in a sample of Chinese undergraduate students. Our findings sugges<sup>t</sup> that conscientiousness is a robust and prospective predictor of subjective and physical well-being, but subjective and physical well-being were not prospective predictors of conscientiousness. The present study contributes to an in-depth understanding of the conscientiousness-health relation. Promoting conscientiousness in future health-related interventions may help to foster better physical and mental health for undergraduate students, especially for those with low conscientiousness.

**Author Contributions:** Conceptualization, Z.W.; methodology, Z.W. and Y.H.; investigation, Y.H.; resources, Z.W.; data curation, Z.W.; writing—original draft preparation, Y.H.; writing—review and editing, Z.W., Y.H. and Q.F.; supervision, Z.W. and Q.F.; project administration, Z.W.; funding acquisition, Z.W. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was supported by National Natural Science Foundation Grant of China (31971004), and the Research Program Funds of the Collaborative Innovation Center of Assessment toward Basic Education Quality at Beijing Normal University (2022-05-004-BZPK01) awarded to Zhenhong Wang.

**Institutional Review Board Statement:** The study was conducted according to the guidelines of the Declaration of Helsinki, and approved by the Academic Committee of Shaanxi Normal University (202002018).

**Informed Consent Statement:** Informed consent was obtained from all subjects involved in the study.

**Data Availability Statement:** The data presented in this study are available upon reasonable request from the corresponding author.

**Conflicts of Interest:** The authors declare no conflict of interest.
