You still have a lot of time.
Don't be in a hurry to find "the one", because the time will come. Stop looking so hard and let it find you. Everyone is in a hurry to grow up, or drink, or get married, when we still have so much time to do all that. If you want to take a spontaneous trip, just do it. There probably won't ever be "the perfect time" to take your dream vacation.
You still probably have no idea what you want to do with your life.
Whether it's changing your major, making a big move, quitting your job, or making a major life decision, you probably aren't 100 percent sure its the right thing for you yet. There are always new opportunities coming up, so find one you'll love.
You don't deserve anything.
I'm not sure if it's our generation, the media, or if it's just an "American thing," but we seem to think that we deserve everything we want, when in reality, we don't. What we deserve are the basic necessities that other people don't have, like food, water, shelter, and adequate clothing for weather conditions.
You're bitter about things that no longer matter.
You're still mad at that one professor for giving you a B, or not making the varsity basketball game, or mad that you gave that guy your number and he never called you back. Focus on the great things to come, not the great things that never happened to you.
Not everyone sticks around.
People lie, friends can betray you, and strangers take advantage of you; but, there are also the people that would try to move heaven and earth for you. Enjoy your time with the people who matter, forget about the ones who never did, and remember the friendships that fizzled out. Only true friends will stick around anyway.
Your parents are getting older, too.
This one really hits me hard. One day, your parents are going to be your grandparent's age, and you'll be the one always worrying about them, even thought they'll still be worrying about you.
You need to have a better relationship with your parents.
You've probably taken your parents for granted a few too many times. We're so used to having them around that we forget that there are people who have lost theirs. Try and make an effort to call your parents at least once a month because they'll always worry about you, no matter how old you get. Take them out for dinner or coffee every once in a while, because it will mean more to them than you think you know.
Your siblings grew up way too fast.
Where did the time go? They're already asking you important life questions, yet you still only picture them in their rain boots playing outside and asking you what words mean. They never stop growing, just like you. You want them to stay young and innocent forever, and you never want a single bad thing to happen to them.
Life is unpredictable.
Life is scary, unpredictable, and definitely not easy, but don't let that be an excuse. We're on the brink of WWWIII at least once a year, and there are faceless organizations trying to strike terror in countries around the world, but there is always hope. Don't live in fear, but live in the moment. You always have options, so I hope you never feel trapped in a corner. Do the things you really want to do in life, even if it seems impossible; it never hurts to try. Life is strange, but its a beautiful thing. Live life to the fullest, and enjoy every minute of it!