**2. Methods**

#### *2.1. Participants and Procedure*

Undergraduates from a university in northwest China were recruited by posting flyers around the campus and online. All participants were informed that the purpose of this longitudinal study was to investigate undergraduate students' subjective and physical wellbeing via questionnaires. They reported voluntary participation and provided informed consent prior to the study, following which they were asked to complete a series of questionnaires in 2 waves during the period of the investigation. A total of 420 valid questionnaires were collected in the first wave (at T1: 16 September 2018 to 28 September 2018) from 282 females and 138 males. The mean age of the sample was 18.98 years (*SD* = 0.96) ranging from 17 to 25 years. After 1 year (at T2: 13 September 2019 to 27 September 2019), follow-up telephone or e-mail invitations were sent to the 420 participants inviting them to participate in the second survey wave. Data from 55 participants were excluded due to incomplete responses, academic interruption, internship search, or other matters. Ultimately, a total of 365 valid respondents ( *<sup>M</sup>*age = 19.95 years, *SD* = 0.93, range = 18–26 years old; 67.95% females) participated in the two waves. There were no age differences between males and females, *<sup>t</sup>*(363) = 0.174, *p* > 0.05, Cohen's *d* = 0.02. The participants who did not participate in the second wave were not significantly different from those who participated in the two waves in terms of any T1 measures (for age and the main study variables: all *t* values were less than 1.31, *p*s > 0.05; for gender and other ordinal demographic characteristics, all *χ*2 values were less than 6.44, *p*s > 0.05).
