As we aim to accomplish desirable goals, challenges, and hurdles are omnipresent. These point to a discrepancy between current and hoped-for states, produce negative emotions and are aversive. Regret relates to one such discrepancy. Developmental theories postulate that opportunity to overcome these effects is plentiful in young adulthood. The main aim of this dissertation was to ascertain the emotional and motivational processes inherent in the regret experience across time in young adults. An additional focus lay in understanding the benefits of continued engagement in overcoming regret, despite pessimism in one’s odds. Finally, these analyses were replicated in an older adult sample to assess their specificity to young adulthood. 
Study 1 assessed the associations between intense negative emotions, regret engagement, implementation intentions, progress, and well-being measures over time among 121 young adults. Results indicated that regret intensity predicted increases in well-being and reduced intensity over time, through increases in regret-related progress. Additionally, increased engagement at onset and increased in implementation intentions over time mediated the increases in regret progress. This illustrates that emotional intensity can positively affect regret-related progress, and thereby well-being and distress over time, through its motivational effects.
Study 2 followed 121 pessimistic young adults to assess the benefits of continued regret engagement, despite reservations. Results showed that pessimistic participants who continued engaging in their regret displayed well-being improvements, which were mediated by improvements in their outcome expectancies over time. This points to the importance of continued pursuit in overcoming regret on well-being in pessimistic young adults. 
Study 3 replicated these analyses in an older adult sample of 136 community dwelling recent retirees. Results showed that the experience of regret intensity was linked with increased intensity over time, but not with other variables. Additionally, pessimistic older adults who continued to engage in overcoming their regrets did not display expectancy or well-being improvements over time. This suggests that regret-related benefits are specific to young adulthood. 
This research contributes to the literature on adaptive development across the lifespan. Findings on differing adaptive responses to the regret experience are explained with the use of developmental and motivational theories.