At 17-years-old, Calif. native Johnny Strange is the youngest person ever to conquer the tallest summits on each of the seven continents.

After topping the final peak last week, Strange e-mailed family and friends to say: "Never let anyone stifle your dreams no matter the feat, for if you have the heart and the courage, impossible is nothing."

He shouts another message from the mountaintops as well. A sign he carried to the Mt. Everest peak read, "Stop Genocide."

Watch the Katie Couric interview at CBS.