I have a postcard with a single word on it tacked to the small bulletin board above my computer. The word is ANGST, and it is rarely more appropriate than when the end of a semester is nigh.
One moment I'm euphoric: this research paper/project/essay is going so well! I'm an academic genius! The next, I'm in the depths: this research paper/project/essay is an utter failure. Who do I think I'm kidding?
It is altogether energizing, frustrating, stimulating, intriguing, maddening and gratifying.