1. Don't make fun of how someone laughs or eats — they may never want to do either one around you again.
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2. No one has the answers, and everyone is faking it most of the time.
The older you get, the more absurd it seems that you once thought people your current age were "adults" who "have their shit together."
3. If you ever have to put down a beloved pet, stay with them in the room until it's over.

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The feels. =(
4. You can and should end toxic friendships, even if you've been friends for your whole life.

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5. It's totally OK to fail, or to be bad at something.

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6. No one is invincible.

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7. Don't be a jerk.
8. Buy clothes that fit you NOW, not clothes you hope will fit after you lose weight in the future.
9. Form your own opinions about people — don't just believe what other people are saying about them.

10. Live below your means, and always try to save something out of every paycheck if you can.

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Services like mint.com can help you set budgets and save more.
11. Don't play hard to get.

12. Only ever have sex with people who have given enthusiastic consent.
13. Measure your front door and stairwells before you buy that couch.

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Otherwise you'll be calling the Couch Doctor. Or just leaving it on the sidewalk, because where else is it gonna go?
14. If you're always complaining about drama, you might just be the one who's creating it.
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15. Talk to your family and loved ones as often as possible when they're alive — because they won't always be.
16. Everyone is as uncomfortable and uncertain as you are.

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17. Your parents are fallible humans and make mistakes sometimes, and that's OK.

18. Never assume malicious intentions if you haven't yet ruled out mistakes, incompetence, neglect, or plain old thoughtlessness.
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Most people are not trying to be assholes, and most people are also totally fallible.
19. It may feel like the end of the world now, but it very likely won't feel so terrible in 10 years.

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