There’s a saying: “Father Time is undefeated.” There is no escaping getting older. You may feel 28 mentally, but the sounds you make just by getting up from a chair can be a sobering reminder of how advanced you are in age.

Photos of mementos and references from your youth can also reinforce that feeling you’ve gotten old, and pretty quickly. This subreddit is filled with these posts, making many people who see them curse under their breath after realizing how quickly all those years flew by.

We collected some of those posts for your reading pleasure today. While they may bring in some nostalgia, don’t be surprised if you also feel a palpable sense of wistfulness.

#1 Who Recalls These Shin Shredders?

#2 No Holidays

#3 These Were The Rewards When Doing Kitchen Duty During My Elementary School Years

As young kids, most of us were in a hurry to grow up. Many were antsy to grow up and enjoy the freedoms adults had, and it felt like time moved at a snail’s pace.

But as we grew older, it suddenly felt like years zoomed by in ways we could no longer keep up with. Human development researcher Jamie Jirout has an explanation.

#4 If You Met This Guy Through His Faster Cousin, I Know Where You Were On Saturday Morning

#5 56 Years Ago Today

#6 Can Anyone Else Relate?

“When we are young, there is so much changing in what we know about the world, and the experiences we are having are so new, we don’t know what to expect,” Jirout said. “The experiences when you are 5 are much more likely to be new and require a lot more cognitive effort to process.”

Jirout adds that being young means you're not good at controlling attention or knowing what to focus on. As a result, you encode more details from your experiences than adults do.

#7 When You Wanted That California Blonde Hair Back In The Day

#8 If This Was Your James Bond, You Belong Here

#9 If You Say You Don't Miss The Old Pizza Hut You Are Lying

We all accumulate experiences as we grow old, which means we develop a better understanding of life and the world around us. According to Jirout, this leads to less novelty in our experiences, so we pay less attention to what is happening.

This is why, she says, time can feel like it passes much faster when we reach adulthood.

#10 If You Recognize This Woman…

#11 Have You Ever Driven A Car Or Truck With 3 On The Tree?

#12 Before Email …

That feeling of the years going by so quickly also has to do with how our brains interpret time. According to Queensland University of Technology psychology and counseling professor Hinze Hogendoorn, it’s because our brain estimates the passage of time through changes.

“Unlike a clock, the brain does not have regular ticks to count,” Hogendoorn wrote. “To infer how much time has passed, the brain simply adds up how much happened. If you fill a time interval with exciting stuff, it seems to last longer.”

#13 Ah The Drive In Movie Played This One!

#14 If This Was The Air Conditioning For You Car... You Know What I'm Going To Say

#15 Are You Old Enough To Know Why We Had Two Car Keys In The Old Days?

A routine can also make time pass more quickly, Hogendoorn says. Again, a lack of novel experiences comes into play, leaving less vivid memories.

“When our older brain therefore looks back to infer how much time has passed since the start of the year, it concludes that not much has happened, so it doesn’t feel very long ago,” he explained.

#16 I Miss Unloading My Groceries On To One Of These

#17 Who Drank This In The Early 80s?

#18 Larry, Darryl, And Darryl

It’s likely safe to assume that everyone will jump at the chance to turn back the clock. But since time travel isn’t possible (yet), we can slow down time. Hogendoorn’s advice: just get bored.

To keep memories fresh, he says it’s all about rehashing every one through journaling or simply reminiscing. As he notes, “Keep your memories alive, and you’ll keep your past alive.”