It's mainly about working hard and proving to people you're serious about it and stretching yourself and learning. The mistake a lot of actors make particularly young ones is allowing themselves to feel that they're the finished articles the bee's knees and it's not true.
I kind of fell backwards into acting. I was studying to be a high school teacher. I look now and I understand completely or actually barely how much work it is to be a teacher. It's an incredible amount of work.