Your 30s is also when many college and grad school graduates finally pay off their student loans. Reroute your former student loan payment to other debt (or, better yet, invest it in an IRA or taxable account) for another pain-free method of saving. (Finally) Roll Over Your Old 401(k). John, who runs the personal-finance blog ESI Money and retired at 52 with a $3 million net worth, has interviewed 100 millionaires over the past few years and found that the median millionaire.

Hey you — 20-something socialite with a Starbucks in your hand.

On your way to work after being out all night? Is that smudged eye makeup and a guilty smile turning up the corners of your mouth?

Time to listen up. I am the voice of your future. Ever wanted a crystal ball to see what's around the corner when you hit yours 30s? Well, you don't need one. Check out this list of 30 things that will happen in your 30s .. whether you like it or not.

1. Your ass will drop.

Sorry, hot stuff, but your ass is going to drop by a notable amount.

If you pound the iron at the gym and don't over-indulge on empty carbs, then it will stay higher for longer. If you have kids, then you're f'ed. It heads south like a flock of birds for the winter.

2. Fear will set in.

Age is just a number, right?

You're as young as you feel .. or whatever you need to tell yourself to gloss over the fact that you're just a hop, skip and a jump away from middle age. Ouch.

Fear will start to set in about anything and everything, but mostly about the fact that time is running out. It's finally dawning on you that if you're going to be the next Mark Zuckerberg, you need to get a move on.

3. You get commitments (again, whether you like it or not).

Unless you want to turn into the crazy cat lady, you'll have to compromise part of yourself just to be able to emotionally tolerate another person.

Even if you reject society's model of marriage and kids, you'll still have to be an aunt or godmother, or look after your ailing parents or manage a business.

You'll get commitments, even if they're thrust upon you.

4. You can be really negative at times.

Being broken up with via WhatsApp, passed over for promotion or watching it rain on your wedding day can make you really negative.

Without realizing, you start expecting the worst to happen. Your deep sarcasm is usually funny, but sometimes you're just plain pessimistic.

5. You start looking back.

Best way to avoid looking back at the past with regret? Seize every opportunity that comes your way. Learn to embrace your present without wallowing in your past and your college days.

6. You'll need more stuff.

Staying the night at someone else's house becomes a project that has to be planned. You can't just go with nothing but a lipstick and a cell phone in your purse, trust me.

7. You feel hangovers the night before.

Hangovers suck — and for some reason — as you get older, they get uglier. So ugly, in fact, that you start anticipating them the night before.

This means you also start drinking less and going home earlier.

8. You'll gain new respect for your parents.

Your parents are pretty annoying in your 20s.

Your mom calls at the most inopportune moments — 69, anyone? — and your dad scolds you about not saving for your pension.

You spend your 20s avoiding their phone calls and blaming them for screwing you up. But by the time you cruise into your third decade, you can remember them when they were your age — scary and eye-opening all at once.

9. You'll wish you hadn't fallen asleep with your makeup on.

If you're a serial lazy girl who falls asleep with your makeup on, then do yourself a favor and start taking it off.

You may think you're not going to care about how you look when your older. Here's a newsflash for you: You will.

10.You start growing facial hair.

If you've never had to wax your mustache before, you probably will in your 30s.

Even if the hairs around your upper lip are tolerable, you'll start seeing random wiry ones sprouting from your cheeks or forehead.

11.You get technophobic.

Wait – what? Technophobic?

How could you ever fall out of love with all things apps, chats and online groups? You will when suddenly the generation behind you starts to find new ways of having fun online.

You'll have a hard time trying to understand them. You'll also get more resistant each time Apple runs another iPhone update.

12.You'll wonder why you enjoyed being loud in a nightclub.

The idea of staying up past midnight in a sleazy bar with strobe lighting and pounding music will become abhorrent to you.

You will question how you ever enjoyed that kind of thing and where you got the energy from.

And if you do break your schedule and have one of those nights out, remember I warned you about the hangovers.

13.You drink better wine.

You'll no longer slosh down any old liquor handed to you.

You'll become more discerning when it comes to wine and start to actually notice the flavors. You'll opt for the wines that don't leave stains on your teeth and you'll drink it slower — out of a glass.

14. Money becomes more important.

If you're not really bothered about money right now, you will be later on.

Buying that better wine becomes expensive.

That advice your dad kept giving you in your 20s about your pension? It starts sinking in now and you'll need more money to stash some away.

15.You need more things to sleep.

Stress, tension, panic attacks — you've probably had all those at some point.

You know when your brain starts whirling around non-stop as soon as your head hits the pillow? That gets worse with age and you find you need more things to sleep.

From a bedtime routine to a pitch-dark room, earplugs or meditation, sleeping's not as easy as it used to be.

16.You get treatments on your back.

That was the first time I felt really old — when my back went out.

Your body doesn't respond to things as it did before. That spontaneous back-flip you did to impress your nephew? Not a good idea.

17.You forget that you're older than everyone else.

You've grown up in a world where everyone else is older than you: your parents, your teachers, your first, second or third significant other, maybe the mature circle of friends you hung out with in college.

So, you continue to assume that everyone you look at is older than you. You forget that while you were living your life, new people were being born. And they're not kids anymore, or even your assistant.

The day you realize that your boss is younger than you, I suggest Bourbon over ice.

18. Your sex drive increases .. and then almost disappears.

You've heard on more than one occasion that a woman reaches her sexual peak in her early to mid-30s. Woo!

There has to be something good about getting older, right? But get ready for it to plunge off a cliff when you have kids, a demanding job or maybe even both. Less Marvin Gaye and more The Animals.

19. You go to bed earlier.

You know how in your 20s you can do all those social gatherings, sleep five hours and still function at work?

As you cruise into your 30s, you start having a harder time doing this and start going to bed earlier — having dinner earlier and maybe even preparing your outfit for the next day the night before.

20.You realize how fast time goes.

You get all misty-eyed as Facebook reminds you of boyfriends past and you realize how fast time goes.

Then you say it out loud and end up showing your age, sounding like a rambling old lady waiting at a bus stop.

21.Your parents need to be taken care of.

At some point in your 30s, you'll get a phone call to say that your mom's had a fall, or your dad needs an operation. Well, hopefully you won't.

But in one way or another, the roles start to reverse and you begin worrying more about your parents than they do about you.

Whether it's explaining how to send a text, work the new microwave or visit them in hospital, you'll start to realize you're the one taking care of your parents, not the other way around.

22. Your tolerance for bullshit is almost zero.

You can smell bullshit from a mile away and read through people's intentions more easily.

And better yet? You actually have the confidence to follow through.

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