Hello. 18 is young to decide what your going to be in life. But a good time to start. I wouldn't worry about being anything other than pleasant to people for the time being. Because if your going to be an actor your really going to need it through thick and thin, disappointment and dismay. You may find that 'serving other people' may have a different meaning -
Mark Ruffalo - Biography.
I like your enthusiasm. If you keep this up, this is what will make you.