Relax.
When in doubt, just take a breath. Take some time away from everything stressing you out. Get off social media, put some music on, and just let it be quiet for a minute before resuming whatever you were doing. I personally like the quiet place website.
Spend some time outside!
Seriously.
Count to 3 and get out of bed. If you can't go out, then at least look around or out the window for a minute or two. It helps!
DRINK WATER.
When was the last time you had water? If not recently, go get some! I'm a student and can say that drinking more water actually helped in being motivated and energized.
Talk to your friends!
Talk to someone. If you've been keeping everything inside, let it out. And if you don't have anyone you're comfortable with talking to, journal!
Journaling
Journaling is a great way to express your emotions and to sort out your mind. It's very helpful to vent/rant. Write about whatever you want. What did you do today? How do you feel? You can also audio record (talking/whispering) if you don't want to write.
Sleep!
Studies show that sleeping from about 11:00PM to 7:30AM is a biologically good teen sleep schedule. If you normally stay up past midnight, try gradually adjusting to sleep earlier to improve your mood and energy levels during the day.