Since I’m only in Middle School, I don’t have any fancy equipment and if I go use my mom’s treadmill she’ll ask me what the hell I’m doing at 5:30 in the morning in the basement! So, as a kid, what exercises should I do?

The best type of exercise for someone of Middle school age is bodyweight excersizes, like push ups, sit ups, jumping jacks etc. Yoga is also really good. Make sure to move within a comfortable range, listen to your body and modify when needed.