I came across this quote from legendary soccer star, or footballer, Edson Arantes do Nascimento, perhaps known better as Pele. Although he spoke this in the context of soccer, or football, I believe it applies perfectly to the art of teaching.
Success is no accident.
It is hard work, perseverance, learning,
studying, sacrifice and most of all,
love of what you are doing or learning to do.
Interestingly, and perhaps not surprisingly, the quote applies perfectly to students and their academic success, too. The more a teacher fits the above description, the more the quote applies to his/her students, too.