Take a good look at yourself in the mirror ... that person is disappearing in front of your eyes. And you know why? Because you are slowly but surely turning into your parents. Sorry.
Oh, it may seem far, far off -- you can't imagine the day when you'll see gray hair and hear yourself saying "when I was your age" -- but rest assured, those things that everybody likes about you will fade away and you will become a shell of the person you once were and you'll start to weep before you eventually come to accept it. Why exactly does this happen?
Your hormones balance out and you feel less passionate about stuff...Getty Images
Wanna fight the world? Sure, everybody does ... until they wake up one day and realize they want things to stay the comforting same. When we're younger, our hormones are boiling red-hot, which can increase our anger levels, so we want to have a beef with the system and take down "the man." But when we get older, we mellow out and decide that we like the way things are because that's how we grew up with them and that's how we want them to stay. So there.
...but those plummeting hormone levels can also make you grumpierGetty Images
Dopamine and serotonin are chemicals that make you feel good, and when you do things that you like, your body makes more of them. Unfortunately, as you get older your body makes less of them, and if researchers are right, you start to be a crotchety old fart just like your old man.
So if you wonder why nothing makes your dad happy, it's because his body won't allow him to be -- and that's how you'll be someday too. Scary, right? Well, try to stay active and hope for the best.
Our brain's pleasure center requires less excitementGetty Images
What's that mean? It means you don't need much to make you happy on the rare times that you'll allow yourself to be. Right now your brain craves excitement, but that fades. Your mom gardens, your dad likes building ships in bottles ... and that's all they need.
No more chasing adrenaline rushes for you, buddy. Nope, maybe a nice Arnold Palmer will make your day. Wave goodbye to dreams and hello to complacency.
Your tastebuds give upGetty Images
Enjoy food while you can, because before you know it, nothing will taste good anymore and you'll be sipping pea soup all day. How things tastes won't matter, because no amount of salt or sugar will make a difference. You now complain about the restaurant where everyone else just had the best meal of their life.
All the time is naptimeGetty Images
Your parents are always tired, and soon you'll be joining them in going to sleep early. (Except not literally joining them, we hope.) As we get older, our bodies produce melatonin less frequently, so you'll want to have a 4 p.m. dinner and be in bed by 8.
Teens produce more melatonin in the morning, which explains why they drag their ass to school and sleep through first period. When you get older, you'll be up at dawn and sleeping by dusk. Goodnight, party animal.
Bye-bye, musclesGetty Images
Wonder why you are slowly looking like a potato that has four toothpicks in it? It may have something to do with the fact you are lazy, or it could be that your testosterone levels are on the decline. It seems like your body doesn't want to make much of anything when you get older, but what can you do? (Besides watch all of your muscle tone fade away?)
I smell old peopleGetty Images
As we age, our bodies produce a chemical called 2-Nonenal, and unfortunately it can give us a grassy, headed-toward-the-grave odor that'll never be tamed. Yo pops, you stink!
Talk about the good ol' days ... REPEATGetty Images
"Man, that really takes me back." Get used to saying that ... because you will. And maybe there's a good reason: nostalgia triggers a chemical release that makes you feel good while focusing on a memory that made you feel good once (and can again and again). The best part is the older we get, this ancient memory seems to get better, because we don't remember it the way it really happened. So the next time your parents wax on about the past, gaze into your future.