<p>Physical activity supports both physical and mental health, yet many people struggle to act on their intentions to stay active. One possible explanation is exercise procrastination. This study was focused on the role of meaning in life (MIL) in exercise procrastination, aiming to uncover the underlying mechanism through the lens of self-regulation. A 14-day daily diary study was conducted among 186 university students (55.9% female, <i>M</i>_age = 20.66 ± 1.67) in southern China. Daily assessments included MIL, exercise procrastination, positive affect, and outcome focus. Multilevel mediation analyses were conducted to examine the mediating roles of positive affect and outcome focus. The results showed that daily MIL negatively predicted both the subjective (<i>B</i> = -0.20, <i>SE</i> = 0.04, <i>p</i> &lt; .001) and relatively objective (<i>B</i> = -0.45, <i>SE</i> = 0.12, <i>p</i> &lt; .001) indicators of exercise procrastination. Furthermore, positive affect mediated the relationship between MIL and subjective exercise procrastination (effect size = -0.07, 95% CI = [-0.114, -0.035]). Outcome focus also significantly mediated the relationship between MIL and exercise procrastination, for both subjective (effect size = -0.06, 95% CI = [-0.093, -0.032]) and relatively objective measures <i>(</i>effect size = -0.14, <i>Posterior S.D.</i> = 0.06, 95% CrI = [-0.263, -0.029]). The present findings shed light on the positive role of MIL in alleviating exercise procrastination and elucidate the potential mechanism from the perspective of self-regulatory resources. Interventions for exercise procrastination could be designed based on the self-regulatory role of MIL.</p>