As we age, regrets may pile up while chances to turn back the clock shrink. It is an unfortunate combination, and one that psychologists want to understand better, especially through the lenses of regret and rumination. Do you know that feeling when a missed opportunity nags at you? That is regret, but it often brings along rumination: the tendency to repeatedly think about your feelings and thoughts. Together, these feelings can form a self-sustaining cycle, impacting mental health and even one’s sense of purpose in society. This study dived into the interplay between regret and self-critical rumination among the elderly, trying to understand when and why these feelings of regret intensify. The researchers also looked at whether regret serves as a mediator in the relation between pre-task state rumination (a brief moment of these thoughts) and post task state rumination, and whether trait rumination (a characteristic) moderates this mediation. Researchers in Belgium recruited 56 cognitively healthy older adults, all over 65, from Flanders. Each participant completed a questionnaire (the SCRS), performed a computer-based “Devil’s Task,” and then wrote a short reflection. The aim was to see if task results would spark feelings of regret, and to check if certain ruminative traits made people more prone to regret. Using a linear mixed model and mediation analysis, they assessed whether regret could bridge the gap between pre- and post-task rumination and whether this effect depended on the tendency to ruminate. The results were striking. Both the type of outcome and ruminative tendencies played a role in triggering regret and higher levels of trait rumination and pre-task rumination led to more post-task regret. Unsurprisingly, the worst task outcomes brought on the most regret, followed by suboptimal outcomes and then optimal ones. The Devil’s Task showed that regret rises in response to poor outcomes, consistent with the idea that missed goals (blocked goals) intensify regret. The study reinforces that regret and rumination are partners in a self-sustaining cycle in the elderly, with each amplifying the other. Interestingly, two pathways were identified where regret served as a bridge: one linking general ruminative tendencies to post-task rumination and another connecting pre- to post-task rumination. The lack of a moderating effect from trait rumination means that it did not matter if a person ruminated a lot or not, they experienced this cycle similarly and the bridging effect of post-task regret still remained. Given the impact of this cycle on mental health, interventions for older adults may need to take regret and rumination into account to help break the loop and promote better well-being. So next time you are tempted to dwell on past choices, remember: learning to let go might be just as important for future happiness as the choices themselves. This research is undoubtedly valuable for the community because everyone has tough days now and then. We all recognize the feeling of regret, that lingering sense that something we did—or did not do—won't let us go, keeping us preoccupied. On top of that, we live in a society that expects more and more from us, constantly overwhelming us with choices. This study specifically focused on older adults, an intriguing population, especially given their growing proportion in society due to aging populations. But the concepts and findings here are universally relevant. Through this thesis, we aimed to demonstrate how these factors—regret and rumination—are connected and how they can mutually influence each other. We showed that this vicious cycle is sustainable and not limited only to those who frequently ruminate. At the conclusion of this thesis, we outline several interventions designed to help people break free from or avoid falling into this cycle. These strategies aim to empower people to come to terms with the choices they have made over their lifetimes and to cope in healthier, more constructive ways.