1. Your job
Odds are, you will not maintain the job you have now your entire life. Your time at the local ice cream stand or your favorite clothing store will come to an end. Your first job is just that: a first job. It taught you responsibility and hard work pays off. Other odd jobs for extra income are also not worth stressing over. Do not feel bad about taking days off to be with family or even friends. Your job will still be there when you come back from vacation; a week off does the body and mind good.
2. Relationships
This is not the time to be settling down. We have a life full of friends, family, school, work, a social life and so much more. A significant other is not essential for your happiness. If someone is not making you happy, leave. You are too young to be making sacrifices for someone who may not even stick around. More often than not, guys of similar age are not mature enough for a relationship anyways.
3. Money
We have many years ahead of us to worry about that green piece of paper. For now, we can learn simple saving tips and learn the value of making our own money. But if you really want that new pair of shoes, buy them. Splurging and retail therapy are okay. Save the real worrying for later when you have your own bills to pay.
4. ALWAYS getting a good grade
We've all heard the saying C's get degrees. Now, while I don't suggest doing the bare minimum to get by with straight C's, I am suggesting it is okay to get one every once in a while. Sometimes other projects and/or papers will be more important than others; it is okay to save yourself from the anxiety and just throw something together to pass, especially if it does not pertain to your major. I am not saying these classes are less valuable, but it's better to choose your battles wisely.
5. The past
Whatever happened, happened. Learn from your mistakes. Let it go.
6. The future
Whatever happens, happens. You will not end up anywhere you weren't meant to be.
7. Anything out of your control
Stuck in a traffic jam? Rain turned your hair in to a frizz ball before school pictures? You cannot control how others drive, nor can you control the weather. Sometimes you have to roll with the punches and make the best out of everything. Turn that half hour traffic jam into a half hour jam session. Turn your frizzy hair into a cute top knot.
Less stress, more happiness.