impulse (n): force communicated instantaneously, effect of a sudden communication of motion, influence acting on the mind motive; sudden determination.
vain (a): without real value; empty, worthless, ineffectual light-minded; conceited. --in vain, to no purpose.
two things i've been thinking about. "vain" just because i've heard it so many times in the past few days. talking..and in reading pride and prejudice.
and impulse. i was just thinking about acting impulsively and then regretting what it is that you did. but then i started to think of that quote "never regret anything because it was once something you really wanted" and while that saying can't be held up very well, i believe it can apply in this instance. can...not always, but sometimes.