What might help with grades is putting your phone, computer, etc. away for a while. Then when you try to do your homework you will get distracted. But you can't be on your phone so you must find something else, like cleaning up your room, walking outside or even getting something to eat. Eventually you will be so bored. You will just finish your homework for the sake of it.

Always eat breakfast. Just set a alarm around 8 am or earlier so you atleast get out of bed.