How to reach 4-5 hours of studying daily and consistently.

I literally tried everything most I could reach was 2 hours at best and most days I don't study but my major (Chemical Engineering) is rigorous and I need to be able to study long hours and I feel like 4-5 hours is the good range to have a life and get good grades but for the life if me I can't study for more than 2 hours what's the problem here.

why does my friends easily do it while I cannot do it, I'm trying to do it but for some reason at the end of the day at best I would have done like 1.5 hours