Someone impetuous acts too hastily or carelessly. Hotheaded, impulsive folks are impetuous.
If you're a careful person who thinks everything through and doesn't act rashly, then you're not very impetuous. Impetuous has to do with doing things on the spur of the moment — and not good things. Being impetuous usually goes along with being impatient and easily angered. If you're impetuous, you act quickly and thoughtlessly when you should just take a deep breath, relax, and think about the best thing to do.