The saying 'time flies' seems to become more of a reality as we age.
One moment, you are a careless child, and then, in the blink of an eye, you are an adult with many responsibilities.
And while scientists have yet to find the answer to why it seems our lives pass us by, they have formulated a theory.
Cindy Lustig, a professor of psychology at the University of Michigan, told DailyMail.com: 'One is that when we are older, we tend to have lives that are more structured around routines, and fewer of the big landmark events that we use to demarcate different epochs of the 'time of our lives.'
Lustig added that we have fewer experiences to reflect on as children.
For a five-year-old, one year is 20 percent of their life packed with experiences as they discover the world around them.
However, the same amount of time is only two percent of a 50-year-old's life that likely has fewer new experiences.
Lustig explained that our brains combine similar days and weeks, which seems like everything blends together.
Humans gauge time by memorable events; as we age, those are few and far between.
This is why most people can recall something they have done once rather than hundreds of times.