Answer:
He never gives up.
Discussion:
His determination to walk was indomitable. At home, when he was not in bed, he was confined to a wheelchair. One day, he threw himself from the chair and pulled himself across the grass, dragging his legs behind him. He reached the picket fence, raised himself up and then stake by stake, he began dragging himself along the fence, his resolve to walk undeterred. He did this every day, with faith in himself that he would be able to walk unaided. With his iron persistence and his resolute determination, he did developed the ability to stand up, then to walk haltingly, then walk by himself and then to run.