Learning to teach and teaching itself can be fun, but it’s not always easy. You have to get through your course, find a job, figure out bureaucracy, and deal with problem students alongside the great ones. Sometimes getting through a two-hour class requires an insane amount of effort.
You will need to design interesting, balanced lessons. Your students may be adults, but the are adults who have just finished an eight-hour day at work.
People like games – even if they don’t like to call them that – and you need to adapt more boring book work into fun, communicative activities.
You need to be able to put yourself in the place of your students and decide: Are you speaking too quietly? Clearly enough? Using too much slang? How would you feel being asked to do what you are asking your students to do? All that said, you will go crazy constantly thinking about this stuff; there comes a time when you will need to just turn it off and “be”.
That’s a question mark. Certainly it helps. You will be standing up and speaking in front of groups of people and interacting with them. However, as a not-so-extroverted person who has had a good deal of success as an English teacher, I don’t think this quality is the most important. Many modern methodologies stress that the teacher’s role is to motivate the students to speak. The students, after all, are the ones learning English, the ones who need to practice. Some agencies go so far as to say the teacher in a communicative class shouldn’t be speaking more than 20% of the time. The ability to set up a class so this happens is not linked to your personality, but to your ability to put a methodology into practice. People who don’t have typical “teacher personalities” can also do well teaching English.