You don't have to think about it nearly as much. That's what we call learning. Habits have their dark side, too. They can stifle your creativity, prevent you from taking advantage of new opportunities, and waste a lot of time and money. Habits like cigarette smoking, eating too much fat, and drinking too much alcohol or caffiene can be very harmful to your health.
Most great accomplishments require consistent efforts over a long period of time.
Getting rid of an undesireable habit takes a conscious effort. It is not easy. It is certainly possible, though, and with enough energy and desire can be accomplished. Developing a good habit is difficult work, as well. Any parent knows how much effort and patience it takes to teach their child to brush his teeth twice a day, look both ways before crossing the street, wash his hands before eating, other things like that.