When you are young, the days seem to last forever.
But as our lives get busier, the feeling that life is passing you by becomes more and more prevalent.
"When we are young, we have a lot of firsts," psychologist Meredith Fuller told ABC Adelaide's Afternoons program.
"We have less time on the planet to anticipate it, so it feels like we are waiting a long time [for things to happen]."
As we age, we experience more, and major events begin to take prime position in our memory.
"Very key things are emotionally charged, and it does feel like yesterday because it is significant to us," she said.
Everyday events mostly go unnoticed.
"We become so overstressed that our bodies don't register time," Dr Fuller said.
Dr Fuller said many in the modern world struggled with living in the moment.
"If we don't learn some mindfulness and a way to be in the moment, it really does feel as though time is just racing by," she said.
She said the art of slowing down and not multitasking as often was a way to claim back time.
"When we notice all the little bits and pieces that are going on around us, we elongate time," she said.
Dr Fuller also recommended doing simple things such as breathing slower and taking the time to notice how your body was feeling and reacting to things.
She said being relaxed and living in the moment could help people enjoy and savour life more.
What causes the holiday buzz?
Dr Fuller said it was not uncommon to return from holidays feeling as though the days were longer.
"When we are on holidays, all of our senses are on high alert," she said.
"We are far more aware of what is going on internally and externally."
The routine of our day-to-day lives is also changed when on holidays, stimulating the body with new experiences.
"It is really important to always be curious in life and always look for a new or different way of experiencing other people or investigating life," Dr Fuller said.
She said by experiencing new firsts and slowing down to notice everyday events, childhood curiosity can be reignited and quality time can be found.
"The slower we take it, the more we notice; the more we notice, the more interesting it becomes and the more time will elongate," she said.
An alternative theory
Callers to ABC Adelaide, meanwhile, offered another explanation for the feeling.
If a person's life is converted to numbers, they said, at the beginning, you have more time and at the end, less.
Therefore, by percentage, time diminishes quicker towards the end of your life.