All of these things help improve your mood and sense of wellness:
Bring a healthy snack and lunch. Eat regularly during your school day and don't skip meals.
Stay hydrated by carrying a water bottle with you to school each day. Remember to drink water regularly such as before each class.
Aim to get at least 8 hours of sleep a night.
Blue light from cell phones, and screens make it harder to fall asleep, so reduce blue light exposure from your phone, computer, TV, etc at least an hour before bedtime.
Avoid caffeinated drinks such as coffee and soda in the evenings to improve sleep.
30 minutes of walking every day can help boost your mood and improve your health. Small amounts of exercise add up, so don’t be discouraged if you can’t do 30 minutes at one time