Looking back I was clueless about having a mentor.
I imagined a busy person spending hours with me, telling me what to do step by step and being on call when I had a questions.
It looks ridiculous written down, but this is the pervading belief about mentorship.
The truth is however, that if you learn anything from anyone, then they are your mentor.
Alive or dead you can learn the hard earned wisdom of history's most accomplished figures.
Marcus Aurelius has Meditations.
Benjamin Franklin has his Autobiography.
Montaigne has his Essays.
You can pick and choose a mentor that most fits your situations. The sheer quantity of books almost guarantees that you will find a match.
So next time you want some guidance for your next endeavor, your first stop should be the pages between a hardcover.