Self‐control fluctuates from day to day and is linked to subjective well‐being within and between persons

The psychological trait of self‐control has been linked to interindividual differences in subjective well‐being: Individuals with higher self‐control report less negative affect, more positive affect, and higher life satisfaction. However, less is known about how much self‐control fluctuates from day to day and how these fluctuations are related to subjective well‐being. This intensive longitudinal study describes day‐to‐day fluctuations in self‐control and investigates whether and how they are related to subjective well‐being. A sample of 64 undergraduate students at the entry phase of university (M = 22.55 years, SD = 6.51, range = 18–53, 97% female) provided 1459 reports of their self‐control and subjective well‐being, collected every evening across three 9‐day measurement bursts over 6 months. Participants' self‐control fluctuated substantially from day to day with less than 40% of the variability in daily self‐control being attributable to interindividual differences in self‐control. On days with higher self‐control, participants reported less negative affect, more serenity, and higher life satisfaction. We found no relationship between self‐control and vigor. The findings suggest that researchers need to go beyond current assessment practices and theories treating self‐control as a stable trait to help develop tailored well‐being interventions for everyday life.