The most important event of his life occurred on December 31, 1962. He met his future wife, Jane Wilde, at a New Year's Eve party. One month later, he was diagnosed with a terrible disease, ALS, amyotrophic lateral sclerosis. He was given two years to live at that time. That was 32 years ago. I have had three friends die of this disease. It's a horrible disease. They lasted two, three, and five years, respectively. By anyone's estimation, Stephen Hawking is a medical miracle.
At this point in his life, 1962, Stephen was by all accounts an average-performing graduate student at Cambridge University. Let me quote from his biographers, White and Gribbon, on this point:
There is little doubt that Jane Wilde's appearance on the scene was a major turning-point in Stephen Hawking's life. The two of them began to see a lot more of one another and a strong relationship developed. It was finding Jane that enabled him to break out of his depression and regenerate some belief in his life and work. For Hawking, his engagement to Jane was probably the most important thing that ever happened to him. It changed his life, gave him something to live for and made him determined to live. Without the help that Jane gave him, he would almost certainly not have been able to carry on or had the will to do so.
They married in July of 1965. Hawking himself has said that "what really made a difference was that I got engaged to a woman named Jane Wilde. This gave me something to live for."
Jane Hawking is an interesting person in her own right. I think she decided early on to get into an academic discipline as far as possible from her husband. She has a doctorate in Medieval Portuguese Literature!
Jane Hawking is a Christian. She made the statement in 1986, "Without my faith in God, I wouldn't have been able to live in this situation;" namely, the deteriorating health of her husband. "I would not have been able to marry Stephen in the first place because I wouldn't have had the optimism to carry me through and I wouldn't have been able to carry on with it."