no one knows what will happen. here's how john got to this place. >> two years ago i was running, playing golf. >> reporter: gradually, literally, he began to lose it. >> i started tripping and kind of like a foot drop and started catching my foot on bricks and curbs and started losing my balance initially. and then developed a limp in my right leg. i lost the dexterity where you can't button buttons, tie shoes. i can kick a little bit, but i can't really pick my legs up. >> reporter: john cornic has als, better known as lou gehrig's disease. the nerve cells in the spine and brain that control muscle movement, destroyed. when the brain can no longer tell muscles to move, those muscles wither away.