How to force yourself to study ?

I got my IGCSE exams running through all of may , but i am so demotivated that i cant study , i tried all the stuff that came up when i googled the question , like rewarding yourself , and stuff like that , but they dont work , i am in a really bad mood , this year has been ruthless , and i am tired and sick of studying , what should i do ? its only a month i need some help to study just a bit longer ?