1) Artlessly 2) Automatically 3) Hastily 4) Hot-headedly 5) Impetuously 6) Instinctively 7) Intuitively 8) Mechanically 9) Of your own accord 10) Of your own volition 11) On impulse 12) Rashly 13) Recklessly 14) Spontaneously 15) Suddenly 16) Unconsciously 17) Unthinkingly 18) Without taking cautions 1) Hastily 2) Headlong 3) Impetuously 4) On a whim 5) Randomly 
• (adv.) In an impulsive manner.
Im·pul'sive·ly adverb In an impulsive manner.