Wiki answers says that a human uses 10% of their brains in a lifetime. Now, I can't say for sure (because I can't really think, and I'm sleepy as well as in need of coffee), but I've heard in other places where people only use 3% or less and oh, whatever!
Anyway, today, I feel as though I might have used up all the 10% allocated in about 6 hours, and believe me, the way I'm feeling now is even worse than the time when I had 27 chapters to study in less than 24 hours! It was one of the most exhausting processes in the world (today, and not the day with 27 chapters) The worst part is that I will have to go through the whole process once again tomorrow and I'm dreading it.
And somewhere at the back, my left kidney is protesting against the local drought.