Sandy Hook shooting survivor, now 18, looks back 10 years after massacre in "Note to Self"

Wednesday marks 10 years since a mass shooting at Sandy Hook Elementary School in Newtown, Connecticut, killed 26 people, including 20 children.

Isaiah Márquez-Greene was just 8 years old when he survived the shooting. His sister, Ana Grace Márquez-Greene, was one of those killed.

Now an 18-year-old, Isaiah shares a moving note to his younger self about his life loss in the "CBS Mornings" series Note to Self.