I am doing M.Sc. in Mathematics from a reputed college in India. But I have a humble background in mathematics. At my undergraduate college most of my batch mates were not interested in mathematics, and the teacher taught in a way that we could sail through exams. But I tried to learn on my own from online courses like NPTEL and OCW lectures and somehow I got a position for doing master's. At that time I used to study for just an hour and manage to understand, and I didn't solve any problems.
But here, the teachers are extremely good and they take 3-4 hours of lectures (i.e., one hour for each course). But now I am not able to grasp the concepts (develop intuition, visualization, looking at the big picture, etc.). To understand what my teacher/course instructor taught takes me 2-3 days of work and I am left behind. If I include memorization time then almost a week or so.
I am becoming overweight and suffering from lower back problems. If stay late up at night then I don't get sunlight giving vitamin D deficiency.
I don't know but I know I want to do research.
But how should I deal with this, I have 6 (5courses+seminar under professor).
And here we have to write an exam and be in the top 100 percent to get admitted for PhD from a reputed college with proper funding.
Please guide me, help me. How can I maintain my health and study?