From The Guardian’s obituary (which is really good):
Those who live in the shadow of death are often those who live most. For Hawking, the early diagnosis of his terminal disease, and witnessing the death from leukaemia of a boy he knew in hospital, ignited a fresh sense of purpose. “Although there was a cloud hanging over my future, I found, to my surprise, that I was enjoying life in the present more than before. I began to make progress with my research,” he once said. Embarking on his career in earnest, he declared: “My goal is simple. It is a complete understanding of the universe, why it is as it is and why it exists at all.”
He began to use crutches in the 1960s, but long fought the use of a wheelchair. When he finally relented, he became notorious for his wild driving along the streets of Cambridge, not to mention the intentional running over of students’ toes and the occasional spin on the dance floor at college parties.
The life of Stephen Hawking – in pictures
Hawking’s first major breakthrough came in 1970, when he and Roger Penrose applied the mathematics of black holes to the universe and showed that a singularity, a region of infinite curvature in spacetime, lay in our distant past: the point from which came the big bang.