High school is the best and worst years of your life all wrapped together as one. Not everyone has a bad high school experience like in the movies, but no ones is really a walk in the park. High school is usually where people seem to find themselves, who they really are. You make friends that you expect to keep forever and memories you think you'll never forget. You take classes you have to take because someone told you to and get questioned on why you don't do well in them. You're constantly running from school to after school activities like sports or play practice, or dance. You never seem to have downtime and you never have a boring week or weekend.
Once you walk across that stage, grab your diploma, and shake a few hands things begin to slowly change. You're going to lose friends, people grow apart. The ones you don't grow apart from you will most likely be 100s of miles away from when you head to college. You're going to move away from your parents and siblings, you'll still see them a lot. Worst of all, for some, your after school activities are going to end. No more soccer, dance, band, or whatever you choose to do. But guess what... you're going to make it.
Actually you're going to do better than make it. You're going to make new friends who become more like family, new memories, and a whole new outlook on life. You're going to learn so many new things you never could have learned or understood while in high school. You're going to get involved in new activities and new experiences. You are going to grow from who you were to who you're striving to become. You'll get to take classes you're interested in and learn to reach your dream career. So, don't spend too much time being sad about the people who left your life, the sports that ended, or the big move out to college. Don't waste these four years focusing on the things you lost. Instead, spend these four years in college focusing on the things you want to achieve and the things you're hoping for. It's okay to be sad, but don't let it stop you from enjoying and taking advantage of these years.
So my best advice for you is don't give up, high school can be tough. Don't forget, you find who you are in high school, but you work towards who you want to be in college.