I've come to this conclusion: What makes a great actor is great need. A huge need of acting.
I'm happiest at home hanging out with the kids... Having a family has been my saving grace because I don't work back to back on anything or I'd drive myself to an early grave with guilt and worry for my family, whom I'd never see.
You will encounter many distractions and many temptations to put your goal aside: The security of a job, a wife who wants kids, whatever. But if you hang in there, always following your vision, I have no doubt you will succeed.