Bitch Ph.D. has a really interesting discussion going on why people choose to leave academia. It sure brings back memories. I can't pinpoint when I first started thinking about leaving, but even before finishing my dissertation--from the beginning of grad school, really--I was doing a lot of non-academic things in my spare time and wondering why everyone else was going to conferences or reading lit-crit for fun. I had zero instinct for networking; I figured doing good work would be enough to get me noticed, and I didn't do more than was required. I thought I was a visual artist, joined an artists' critique group, and tried to figure out how to work that into my career. I decided to quit for sure after my third failed foray through the MLA job market. After making calls and finding out I was not invited for on-campus interviews (for two third-tier job prospects), I decided to end it. I hung up the phone, cried, then danced around the apartment, happier than I'd ever felt in my life.
I still envy people in tenure-track jobs, in that they have tangible accomplishments to show for all their hard work. But I don't envy the work itself, or the pressure to perform, which doesn't go away once you have tenure. I can't stand 99% of academic writing, and I don't want to do any more of it myself. I do love teaching, and am grateful that I can teach here at Stanford, where the students are uniformly wonderful.