The wait between Christmases or birthdays when you're a kid feels like an eternity.
Fast forward a few decades, and it seems like barely any time has passed between one year to the next.
Time feeling like it speeds up as we age is a thing, explains Hinze Hogendoorn, a professor in visual time perception at the Queensland University of Technology.
"When you're young everything is new and exciting. First day of school, first car, first relationship, first job.
"There are lots of memorable firsts."
As you get older, however, routine creeps in.
"Cook dinner, pick up the kids … it's busy and important work, but it's not as memorable," Professor Hogendoorn says.
"Each year feels like it has gone slightly faster because you have less [memorable activity] to show for it."
And the perception that time is flying by can sometimes make us feel stressed and anxious, explains psychologist Meredith Fuller.
So can you make time feel slower? And is there any benefit to doing so?
How our brains compute time
"When we talk about other perceptions like vision and touch, there is something out there in the world to be perceived," Professor Hogendoorn says.
For example, eyes detect light.
"But with time perception, there isn't a thing … to be perceived, and we don't have a specialised organ to detect it."
He says that's the "root of where some of these things start to get wonky", because we infer time from the fact that things change.
"Our brain uses the amount of stuff that has happened as a cue to estimate how much time has passed," Professor Hogendoorn says.
"If you look back over the week and nothing has happened, or lots has happened, but it was uneventful and not memorable, unconsciously we decide that we don't really have seven days' worth of memories, so it doesn't feel that long ago."
And more generally, we're just not that good at judging time, explains Professor Hogendoorn.
He says experiments show "it's remarkable how far off people can be. It ranges between half [the true time that has passed] and double."
Can we slow time down?
While it might be an "unsatisfying answer", Professor Hogendoorn says boredom is key to slowing down time "in the moment".
But that's unlikely to make life feel more fulfilling. And conversely, he says to make time feel slower when looking back, you need to do more fulfilling and interesting things.
Professor Hogendoorn suggests having more new and memorable experiences — and making sure you don't forget them.
"Go bungy jumping, do outlandish things that will make you go, 'this was the year I did this crazy stuff'."
To protect them from fading away, he says we need to relive those memories with others, reflecting on what you have done. Or by journalling, for example.
Ms Fuller says while we crave routines, we also thrive on the new, different and unusual — it's a balance.
"If you are feeling like every year is the same, what do I have to look forward to? Where did the last decade go? That tells you your routine has overtaken your need for new, different and exciting.
"That is what is significant to us slowing time."
Slowing down time can be good for us
Mindfulness can play a role in slowing time down, too, which is good for our brains, says Ms Fuller.
But it's not just about sipping your cup of tea, noticing the taste and sound, and observing the environment around you.
"If I am sitting here being very mindful of my tea, but it's the same tea for 40 years," that's not very memorable, says Ms Fuller.
"Yes, be mindful, but you have to try other things."
One of the reasons we can feel stressed about time flying by is our fear of death, she says. Coming to terms with that can help.
"If we don't … accept death, we can really live in an anxious state all the time, worried there is never enough time.
She says rigid archetypes also add to this. For example, if you move through life thinking "I'm a young woman, then I'm a lover, then I'm a mother, then I'm a grandmother and that's my life", there is no room for something new.
"If you open yourself up to different identities, that will help time slow," Ms Fuller says.
