How do people pull amazing grades without studying 24/7

I’m not sure what it is with me, but in order to pull even half decent grades, I have to fully dedicate my whole long on school and studying- I sit at my desk all day (have even gained weight from not leaving my desk) and I just don’t understand how people juggle several different things and still pull amazing grades (better than mine)? They make studying and school look like a side chore.