Dealing with lack of motivation and discouragement - tips?

[Aubs]

I've been testing for a year and a half now and I'm currently working on US History II. US History I was fine, no problems there. This one....I can't seem to grasp it with all the politics and such, they really don't make sense to me and I'm finding it harder and harder to dive in and start studying when I know it's going to take every ounce of my energy. I've already taken a month off since my last test so taking MORE time off isn't really an option.....

I get this way sometimes, especially when I'm facing giant, mountainous tests like this one. I can study and study until my eyes fall out of my head and it just doesn't stick. I do flashcards, read textbooks, even write notes on my arms so I can review them throughout the day and yet, I still don't understand it enough to logically think out correct answers on the test and I end up choosing an answer that's way off the mark.

How do you guys fight those sinking, depressing feelings? What do you do when you're so frustrated with yourself because no matter how hard you study, you just don't get it? What do you do when you feel like you study 24/7 and you're still simply scraping by? How do you find motivation again?

Thanks in advance....