Note: Boot SE, Boot ULCI and Boot LLCI refer to the standard error, upper limit and lower limit, respectively, of the 95% confidence interval of the indirect effect estimated by the percentile bootstrap method with deviation correction, the same below.
Second, the mediating effect of boredom between physical activity and negative mood was tested using Model 4 in PROCESS 3.3 (Model 4 is a simple mediating model). As shown in table 7, physical activity had a significant negative predictive effect on negative mood (β =-0.12,t =-2.70, p <0.01), and after the mediating variable was added, the negative effect was no longer significant (β =-0.05, t =-1.42, p >0.05). Physical activity had a significant negative predictive effect on boredom (β =-0.11, t =-2.55, p <0.05), and boredom had a significant positive predictive effect on negative mood (β =0.61, t =17.39, p <0.01). In addition, the 95% confidence interval for the direct effect of physical activity on negative mood contained 0, but that for the mediating effect of boredom did not. As shown in table 8, physical activity predicts negative mood through the mediating effect of boredom (-0.07), accounting for 58.12% of the total effect (-0.12).