There are three major performance chores for any exciting actor: to create a performance that is (1) emotional honest (the actor truly lives the scene), and (2) logical to the contents of the script (in acting terms, we call both these criteria being "real") and (3) to create a "real" performance that is exciting (audiences come to the theater to be lifted beyond reality. They seek a reality that is memorably exciting (the task of the working actor).
Living reality (theatrical or every day) is exciting when it exhibits emotional intensity and profundity; and when that heightened emotional reality is artistically structured and elegantly moulded and shared, those latter qualities only serve to enhance the overall performance effect.
Exciting human beings (in theater or in everyday life) exhibit several other fundamental qualities: they are goal oriented, and as they pursue their goals courageously to other human beings (in acting terms, they pursue their goals through the other 'characters' in the scene).
To be an exciting actor is also bottom line to be (generally to have learned to be) an exciting person-one who exhibits an many of the personal qualities noted above as possible--and when acting the exciting actor exhibits them on demand, in front of people, and without being inhibited by the requirements saying just these words, moving physically just where the director suggests, and handling the artifacts of the scene (the props).
To manifest the the above acting skills better than more of your competitors is 99% of the time the product of learning, and experienced effort. There is an old--but still insightful adage: To be excellent at any task requires the focused effort of ten thousand hours of effort. 'Don't cheat the gift,' as they say (of becoming an exciting actor; believe me, its in you) by just dreaming of success and not working toward it.
I advise actors to leave the house today and become an acting 'gym rat.'