We hit certain milestones as we move along our lives: learning how to tie your shoes (admittedly, I still struggle with that at times), going to your first day of school, getting accepted into college, earning your high school diploma. Certain lessons, though, take two decades or more to be fulfilled.

1. Not everyone who smiles at you is worthy of your trust.

Just because someone is friendly doesn't mean they're genuine.

2. Life gets easier when you learn to laugh at yourself

Let's face it: we're far from perfect. So why fear failure? Live a little.

3. People come and people go.

Sometimes we stumble across people who make you feel they will be an important part of your life for years to come, but these people have lives and dreams of their own -- lives and dreams that may take them different places than we are now.

4. You don't "owe" any romantic partner anything.

Seriously. Never feel like you have to do something you're not comfortable with.

5. You need alone time. Seriously.

In our teens, we feel the constant need to be social. Once we hit 20, though, we value our moments of alone time. It's necessary for maintaining good mental health, for gosh sakes.

6. Coffee is your greatest ally.

Everyone has a vice. I go for the tall, dark, and hot. Cup of coffee, that is. It gets me through the roughest day and the longest night.

7. Mom was right.

About anything and everything. Start apologizing now.

8. That color really does look awful on you.

Ugh. And those highlights. And that eyeliner. You cringe at some high school photos.

9. Everyone went through an awkward phase.

We look around and compare ourselves to the people who pass us by; they were awkward sixth graders, too.

10. The perfect boyfriend or girlfriend doesn't exist.

Most of us have the image of Mr. or Miss Right carved into our imaginations; no matter how awesome it would be to find the perfect S.O., you can do one better and find someone real.

11.You need to escape your comfort zone.

No one ever accomplished any great act by staying where they feel comfortable. You know to take chances if you want to see a change in the world.

12. Vulnerability does not equal weakness.

Everyone has fears and insecurities. It doesn't make you any less of a person. Yes, it can takes a lot of time to tear down the walls you built up for nearly two decades. But in the end, letting people into your heart may be the best decision you ever made.

13. People have sex.

After that serious one, I felt we needed something lighthearted. So yeah. People have sex. A lot. And they are pretty open about it.

14. You still don't have "adulting" down to a science.

And that's OK. You'll get there. Eventually.

15. You really hate people.

Hence why you need alone time.

16. Budgeting is not fun.

Money is only fun when you have a lot of it. At age 20, that's not likely.

17. Conformity is for chumps.

Why blend in when you can stand out?

18. You need to let yourself have time to just cry.

We tend to bottle up so much emotion just to save face. A good cry makes you feel so much better afterward; just make sure you're not wearing too much makeup.

19. No one really cares if you decide to not drink.

Remember all those alcohol and drug programs you went through during high school? They made it seem as if people would shove cigarettes and solo cups in your face the moment you would walk into a party. So not true. Thanks for nothing, DARE.

20. You're valuable.

You deserve happiness; you're worthy of respect; you're full of life! Spend it well.