Quote from : Back to the Future Part III Movie

Jennifer Parker: Dr. Brown, I brought this note back from the future and - now it's erased.
Doc: Of course it's erased!
Jennifer Parker: But what does that mean?
Doc: It means your future hasn't been written yet. No one's has. Your future is whatever you make it. So make it a good one, both of you.
Marty McFly: [Marty wraps his arm around Jennifer] We will, Doc.