Are you a mentor? Why or why not?

I am doing both my scholarly paper and capstone project on mentorship. I am graduating in May!! Before we graduate we must do six 12 hour clinical shifts with a nurse who acts as a mentor to us and allows us to get hands on experience. So my question is to all the RN's out there:

Are you a mentor?
Why or why not?
Does your facility encourage mentorship?
Is there a structured process or do you just decide independently how the process with flow?

Thank you all for your input!!