I realized I had to get out of there when I had the feeling that every day I was there was taking 2 days off my lifespan.

Shortly before that, I found that letting out a scream when I got to my car in the afternoon was an excellent release.
Before that, I had stabbing pains in my stomach... particularly after meetings which a certain person attended.
And prior to that, I got a new manager who was really toxic and micromanaging. I can't stand being micromanaged. I should have formulated my escape plan right then.

(As for jobs being boring: Yes, they are. I had a perfect job for my first year our of school: I got to move every 3 months to a new department of my choosing. After a year, most of my jobs felt really boring and stale. Sometimes a new project can be rejuvenating.)