The catchphrase "YOLO," (you only live once) has become a bit of a cultural sensation. It is hardly a new idea. The Latin poet Horace coined the phrase "Carpe Diem" in 23 BC. Decades of research on how being aware of death impacts human behavior sheds light on both the good and bad of this ancient idea.
The Benefits of YOLO:
Research on "post-traumatic growth" (started by Ronnie-Janoff Bulman of The University of Massachusetts) has explored how terminal illness diagnoses and near- fatal experiences influence people. After a period of initial shock, many people, perhaps even most, experience profound shifts in terms of how they spend their time, their appreciation of life, and their general sense of happiness. Many of these indviduals report that they feel like they never fully lived until they were diagnosed with a terminal illness. They also report devoting more time to what they most truly enjoy, and not worrying nearly as much about much of what had previously stressed them.
Research on "socioemotional selectivity theory" (Laura Carstensen, Stanford University) explores the way that people devote their time as something - such as life - becomes more scarce. This research shows that as people age (as life becomes more scarce), they tend to devote more time to activitities and relationships that promote positivity and feeling good. They, conversely, spend less time on things that will cause them to feel negatively. This "bias" even is apparent at a basic perceptual level. Older people, when looking at a visual scene, tend to focus more on pleasant aspects of the image than unpleasant ones (relative to younger people). Further, when college students are reminded of death in experiments, compared to a variety of control topics, they then spend more time looking at positive words than negative words when shown both (research headed by Nathan DeWall, University of Kentucky). In sum, when people are aware that life is more scarce, they focus more on positive things, and less on negative things.