A sense of humor ...

In a January 2016 question and answer session, Hawking credited “my work and a sense of humor” with keeping him alive.
“When I turned 21, my expectations were reduced to zero,” he said. “It was important that I came to appreciate what I did have. . . . It’s also important not to become angry, no matter how difficult life is, because you can lose all hope if you can’t laugh at yourself and at life in general.”