I quit because I was not enjoying myself. The students were no longer a challenge. And when I started drinking a quart of sour mash each time I had to grade four sets of essays, life had become too grim. I had to go. What saved me was the courage, or craziness, to start life over at age 49.
Writing is different.
Like several other writers I know, life and work are seamless. We live to write and write to live. A vacation is not rest. It is another means to read, to observe, to talk to interesting people, all for the purpose of writing. Sometimes, you pull to the side of the road and whip out your notebook.