where do people get the enery to go to school everyday?

school started again and i am already tired, im taking the day off today but my mum wants me to go to school more often. i can last for only half the day before i get tired and irritated and sleepy, and i usually get sick the day after. sometimes i physically cant get up the next day but that only happens maybe once every 3 or 4 weeks? i know school is important and i have no issue with the studying but i feel terrible rn and i hate being this tired all the time. i guess i can force myself to go but i dont think it would work. im not very good at explaining things but i am going to try my best. so imagine walking around all day on a bad knee and the muscles in ur neck also hurt and u feel like u havent slept and then a bunch of screaming children run around and give u a headache and while all this is happening u have severe hayfever to the point where ur hands are getting swollen. then usually i get a temperature or vomit from all this, but its too exhausting for me. please help, how do i get the energy to keep going?