(s)driving, impulsivehaving the power of driving or impelling“a driving personal ambition”, “the driving force was his innate enthusiasm”, “an impulsive force”
(s)capricious, impulsive, whimsicaldetermined by chance or impulse or whim rather than by necessity or reason“a capricious refusal”, “authoritarian rulers are frequently capricious”, “the victim of whimsical persecutions”
(s)hotheaded, impulsive, impetuous, madcap, tearaway, brainishcharacterized by undue haste and lack of thought or deliberation“a hotheaded decision”, “liable to such impulsive acts as hugging strangers”, “an impetuous display of spending and gambling”, “madcap escapade”