1. All of your friends move away and you feel like you are alone in the world. - Yes, everyone warns you about taxes and job interviews and all that jazz, but no one tells you that all of your friends move away and you have to coordinate work schedules, time zones, and personal lives just to be able to talk to each other for more than 5 minutes at a time. Basically once you get out of college life does everything in it's power to tear you and your friends apart and it's a shit ton of work to stay friends. They aren't always going to be there to pull you out of bed and make you go out and be social. They also won't always be there to sit on the couch and watch 4 seasons of "How I Met Your Mother" in one sitting while ignoring responsibilities. So you really have to enjoy the time you have with them, enjoy every conversation and enjoy every skype session you get, because sometimes they are few and far between.
2. Student loans are super real. - In college and in high school, student loans, and financial aid and all of that nonsense seemed fake to me. And then last year, when for the first 6 months after graduation my student loans had not kicked in yet, I was loving life. I was enjoying being employed and being an alum and still high on the fact that I had finally graduated college. and then BAM. Student loan payments start and i come down from that real quick. Coming to the realization that a pretty solid chunk of my paycheck each month goes to a loan company. And without getting into it too much, it's one of the hardest things to watch some of my friends who have no student loans get to save up and buy new cars or have nicer apartments or go on cool trips where as I will be writing a check for $XXX to a student loan company until I am least 40. That is scary. and it sucks.
3. Your job/school work *probably* isn't going to be very glamorous. - Sometimes we have these ideas of what life will be like once we are done with the treacherous late nights in college and grueling days of exams and papers and midterms, etc. Weather it's that engineering job at the great firm you have had your eye on forever or working on wall street, writing that book and making a bunch of money, or even just having a fancy office with a great window view, your first few years out of college are not going to be what you expect them to be. So seriously, get used to getting your boss coffee, working late with no overtime, getting put on all the "crappy" projects that no one else wants to do because you have the least seniority, or even having to go to your HR office twice a month because you don't understand your benefits or leave time balances, not that I know yet but I really REALLY like to think that all of those things will pay off one day.
4. Your college major is less and less relevant the older you get. - Yes, there are some majors where you need that degree or that certificate to do what you dream of doing. But then there are some jobs (about 50%) where your college major is completely unrelated and irrelevant to the type of work you are doing. For example, in my example, I work in college admissions. So yes, my degree was great in that it taught me to work with people and all that stuff, but I have coworkers who have degrees in Biology, Geology, International Studies, French, seriously anything. Moral of the story, changing your major isn't the end of the world and if you don't know what you want to do yet that's okay too.
5. Eating right and staying healthy is actually really, really, hard (and expensive) - If you ask me, this whole Kale trend is a conspiracy theory and gyms are just a front for the mafia to make some money. Which you have to buy into either eating like a rabbit or running like a rabbit to stay healthy in this day and age, which both are super expensive. As long as you can have the self control to not eat a gallon of ice cream every week and do some sort of physical exercise you will be okay, but let me tell you, that is WAYYY easier said than done.
6. Your entire Facebook feed is going to be filled with babies/puppies/weddings/and drunk college kids. - Which is super confusing, because you feel stuck in the middle. You are not engaged, you are not pregnant, you are barely making enough money to support yourself in your tiny apartment yet alone pay for a puppy, but also you have real responsibilities so you are not going out every night drinking and partying, and you wake up most days knowing where your keys/wallet/and phone are. You have it together more than the college students you know, but not QUITE as much as everyone who is getting married and procreating. And that is okay, to be honest, enjoy this middle ground. You know where you phone is most of the time, and you don't quite yet have to take care of a tiny human, things could be worse.
But yes, taxes actually do suck (see Rachel Green quote above), figuring out your health insurance is really hard, but also realizing that you can pay for all of your own living expenses and sticking to a monthly budget for this first time in all your years, being an adult can be ~kind of~ rewarding. So enjoy this time, one day we will look back and miss a more simpler time. Enjoy the late nights, and the early mornings, and the job interviews and the grad school applications and getting coffee for your boss because some day, maybe soon or maybe way WAY later, will all be worth it.