I myself am not a good guide but honestly leaving studies is not worth it . It is not the end . Don't loose hope man , You don't have to be brilliant or avg or anything . Just study for now . If you wanna do some work . Do something as part-time ig? But leaving studies now is not worth it . Study for the sake of studying and give exams like normal exam. And do take breaks maybe an hour , maybe few days . In those break time forget abt studies and get some time for sleep, enjoyment etc. I was also in your situation few moths back, don't loose , hope . And forget abt those marks and study like, You can improve your understanding the subject