Ebullient was one of my favorite SAT words when I was in high school. I still like it, and to some extent, it fits me, too (at least, on the good days, or the really bad days).

From the dictionary (m-w.com, dictionary.com) :

e·bul·lient
adj.

1. zestfully enthusiastic.
2. boiling or seeming to boil; bubbling.
3. joyously unrestrained [syn: exuberant, high-spirited]

1. BOILING, AGITATED
2. characterized by ebullience

• ebul·lient·ly adverb

Etymology

Latin ebullient-, ebulliens, present participle of ebullire to bubble out, from e- + bullire to bubble, boil—more at boil

ebullient was Word of the Day on June 30, 1999, April 24, 2002.