I regard studies as a tiresome chore or dreaded punishment.
I try to establish a strong motivation. I must do well!

Yes, either I don't like the subject or I just can't understand it well enough.
No, I just don't want to deal with it.

I do not over schedule and set specific goals and tasks in manageable portion, as well as a definite time for beginning a session or assignment.
I break down large tasks and set reasonable time limits for studying.
I promise myself a treat on completion or forgo a treat if completion of the task is threatened.
I do all of the above.

I like a place that has good lighting and is relatively free from interference.
I like to study in bed.
I don't set aside regular times to study. I do it anywhere and whenever I can.
I study at a regular time, sitting in a well-lit place where there are no distractions.

Yes, I study in 50-minute blocks with 10-minute breaks in between. I also change subjects after an hour or two, and alternate between reading, writing and other activities.
No, I try to stay on the same task for as long as I can take it.

Each time you feel yourself switching off, jot down the time, and take short (5-10 minute) breaks periodically getting up and moving about.
Use a pen or your finger to point to the page and focus your attention, question and evaluate what you are read, recite main points , underline and annotate.
If you are distracted by a problem/task, take a few minutes to note it down, and address it after the study session.
Tackle difficult assignments last.

I study just after a hearty supper and I also drink plenty of coffee.
I don't eat regular meals: I snack on chocolate bars and pop.
I eat regular, small meals and avoid alcohol and caffeine while studying.

I sleep whenever I can afford to take the time.
I establish a regular sleep-and-wake pattern.