Textbook definitions of mentors allude to their trusted positions molded by experience. How their wise perspectives elicit respect as objective confidantes and guides through all manner of situations this life can throw. 

And I agree with those definitions. True and perhaps already proven in your own life. 

But I can only add to these unique individuals' deservedly vaunted status.

Mentors are humanity in its purest form.

Mentors listen because they are selfless. Sympathize because they are empathetic. Avoid judgment because they are tolerant. Challenge because they are seasoned.

Inspire because they are humanity. 

A particular wise mentor in my own life once succinctly pointed out the particular power of professional achievement when melded with balance, passion and excellence.  Then left me with an equally succinct, 'Go do that.' 

So if you have not already, find yourself that special mentor in your life. Or 3. And because we are all humanity, strive to be one yourself every day of your life.

Yes, go do that.