First, nothing lasts forever. Second, stop using Facebook and Twitter, and rest will follow. I wish I knew all this when I was in my 20s. The list is being curated from a great discussion at Quora.com. The ones in bold are my favorite bits. Enjoy.

1. Love is only the beginning.

2. Friends are the best currency.

3. Challenge yourself, no one else really will.

4. No one can push you like you can push yourself. (see #3)

5. If you can’t explain something in a few sentences, then you don’t understand it.

6. Mistakes happen. Mistakes are learning tools.

7. You can’t take back what’s done or what’s said.

8. Take responsibility for what you did and move on.

9. You only have one family. They are not going away. Get use to it.

10. Every little bit counts. A little each day will get most things done.

11. Education only begins with graduation. It never ends.

12. There is always more than one side to anything.

13. Most communication is not verbal. Shut up and observe.

14. Everyone has an agenda. If you know yours, you control yourself; if you know theirs, you control them.

15. Laugh at yourself first. If it is funny, it is funny. So what if it happened to you.

16. Learn your job.

17. What people remember about you most is how you made them feel.

18. Do what you say you will do.

19. Ethics are what you do when someone is looking. Morals are what you do when no one is looking.
(this is a take on Plutarch's quote about Character being what you would do when no one is looking.)

20. You will never understand the opposite sex, just enjoy them.

21. If you have children, you have a lifetime responsibility.

22. You will get older. You can do nothing about it. Just do what love.

23. If you want to argue bring up politics or religion, otherwise don’t.

24. You can learn something from everyone you meet.

25. Admit your mistakes and share your successes.

26. Everyone has an ego. Too much or too little is guaranteed trouble.

27. Don’t believe yourself, believe in yourself. (related to #26)

28. If someone continually says the same thing over and over, you can bet it is not entirely true.

29. If someone talks about others to you then they talk about you to others.

30. Take It Easy - enjoy the moment

31. Count to 10 before taking any big decision or when you feel you will burst with anger.

32. Collect less stuff!

33. Relax. Slow Down.

34. Distrust all authority figures - government, mass media, experts... (my favorite)

35. Build real relationships

36. Spend money on cool experiences over fancy material things.

37. Assume nothing.

38. Disagree with data/facts.

39. Spend more time talking to people of different industries and careers to see what's out there.

40. Use your looks.

41. Your body is a temple (yes, this cliche is true)

42. Start everything early in life - start by saving even 50 dollars/month - the power of compounding is awesome

43. Listen to everyone, and do what your heart tells you.

44. Stay from Echo chambers - give honest criticisms.

45. Internet fame is not real world fame.

46. Stay away from everything organized - organized education, organized religion, cults...

47. Don't get sucked into consumerism - especially cults of things and brands

48. Make a 'wish I had done that' list which you you have read in 10 years' time: And do it now.

49. Don't be fan of any living being.

50. Comic books aren't literature. (favorite)

Related: 50 important rules of life for young people
The best 19 bits of advice for young people and new graduates I ever read

If you liked this, please check out The Success Manual -  200+ top things we all should know to succeed faster in any career.