When things are going well, I hate to quit.
Probably the most profound thing in the Bible is 'Love your enemies, do good to those who hate you.' This is what, to me, is the essence of Christianity.
You have to be taught to hate.
If there's a deadline, I work late. If not, I like to have normal hours, and get up early and work. When things are going well, I hate to quit. And then I'll work 'till exhausted.