Being in your 20s, especially during a time when Millennials seem to be a hot topic of discussion, is tough.

It's this weird limbo stage when you are considered an adult, but you really aren't fluent in adult language or responsibilities yet. You need help filing your taxes. You don't really understand how your 401(k) works. You want to invest because you heard investing is smart, but you don't know where to start. You are financially independent but you're not really sitting on a cushion. You know what you like but you're not really sure if you like it enough to do it for the rest of your life.

It's this confusing time when nothing seems to be set in stone, and yet you feel like you're expected to have everything figured out and ready to go.

As a fellow 20-something, here are 20 brutal truths I had to learn the hard way--and which ended up making me a better person for it.

1. Nobody cares.

Nobody cares if you didn't have enough time. If your toilet flooded. If you weren't feeling well. If you are "going through a tough time." Some people do--they care a little bit, and want to make sure you're OK. But in general, nobody cares. Everyone has "stuff" going on in their lives, and it's on you to figure it out and stay on top of your responsibilities.

2. If you're on time, you're late.

I learned this from a former co-worker, who lived by the phrase: "If you're on time, you're late." He always showed up early and was always prepared. Walking in the door at the last second isn't appropriate. Be early.

3. You have nothing to prove.

I touched on this in another article, but as a 20-something you feel like you have a lot to prove. You don't. Trying to prove how much you know ends up only highlighting how much you don't know. Instead, be accepting of your inexperience and open yourself to acknowledging how much more there is out there for you to learn. It will open the door for those around you to teach you.

4. Reading is extremely important.

It's amazing how many people stop reading books when they graduate from college. Blogs, magazines, podcasts, and documentaries are all great ways to learn. But they do not, and cannot, replace the art of reading. Pick up a book.

5. You are a reflection of the five people you spend the most time with.

If you want to grow and grow fast as a 20-something, one of your primary objectives should be surrounding yourself with people who embody that which you want to become. They will stretch you to grow in ways you wouldn't be able to on your own.

6. You are your most valuable asset.

Yes, enjoy your 20s--but also be aware that this is the single best time of your life to invest in yourself. Instead of destroying your body at the bar every weekend, go to the gym. Learn something new instead of sitting at a five-hour brunch. Study your craft before bed instead of browsing Instagram. Take care of yourself and nurture what is most important to you.

7. Unless you master money, money will master you.

Get the cheap apartment instead of the expensive one. Cook your meals instead of always eating out. Save instead of spending. Learn about investing. Take a portion of every paycheck and put it away for retirement. Don't wait until you're 30 to start being money conscious. Start now. Build good habits so that your money can work for you--instead of you working for money.

8. Achievement is fleeting.

That raise won't make you happy. That promotion won't make you feel fulfilled. That job switch won't change your half-hearted attitude about working in a cubicle. If you don't like what you're doing, stop--because the next carrot will only tide you over for a moment, and then you'll be right back to feeling unhappy. Instead of chasing achievement, do what makes you genuinely happy.

9. There's no such thing as failure.

Failure is the reflection of expectation. Without expectation, "failure" does not exist. Whenever something goes wrong, it is seen as a "failure" only in comparison to what you had expected it to be. There is no such thing as failure. Only lessons. Learn those lessons, move forward, and realize you are better now because of it.

10. It's all about who you know.

Your network is your net worth. Do not take for granted the people in your life who are "connectors" and can provide you access to places and people. Similarly, invest in yourself and your own network so that you too can provide that value to yourself and others.

11. You determine your own success.

Many people see the world through the same lens they used in school, thinking all they have to do is go through the motions, graduating from one position to the next, and then one day becoming the president or a manager and making a nice amount of money. False. You determine your own success. School's over. To get to where you truly want to go, it's on you and nobody else.

12. Practice is not overrated.

If you want to be the best at what you do, you have to practice. Practice, practice, practice. Nothing can replace it. And no amount of talking about it will ever fulfill the quiet and sometimes lonely hours required to achieve what you want to achieve.

13. Not everyone is a "real friend."

Some of your friends are work friends, some are bar friends, some are sports friends, some are gym friends. But not many of those are your "real friends." The difference comes down to who is willing to love you from afar, and give you the space and encouragement you need to walk your own path, successfully.

14. You won't live forever.

Existential, but true. You will not live forever. You won't be a 20-something forever. Be conscious of how you spend your time now, so that you don't wake up at 30 and say to yourself, "How did I end up here?"

15. Vulnerability is sexy.

Want people to like you? Be vulnerable. Want to attract that special someone? Be vulnerable. Want to build real relationships with people? Be vulnerable. The older you get, the more you will realize how much people respect vulnerability--because deep down, we all wish we could be more vulnerable.

16. Listening is a gift you give to others.

Not many people listen, really listen. They stand there and wait for their turn to talk. You can always tell when someone is really listening to you, and it makes you feel heard. Remember to give that gift to others. It will make them love and respect you more.

17. Your word is everything.

If you say you're going to do something, do it. There is nothing worse than someone who makes promises you know they won't keep.

18. The time is not tomorrow. The time is now.

Stop saying you'll do it tomorrow. Tomorrow is today. Do it right now. Success and what you ultimately create for yourself in life is the direct result of how many times you consciously choose not to postpone for tomorrow what you can certainly do right now.

19. You are your own worst enemy.

If you aren't where you want to be in life, audit your own actions before you start pointing the finger. If you aren't achieving what you want to achieve, ask yourself what you are bringing to the table that's getting in the way. Extreme circumstances aside, you hold the keys to your own destiny. It's on you to get out of the way of yourself and bring your vision to fruition.

20. Volume wins.