I quit, fed up and planning to go back to work sometime after a budget travel around the world. Back in town 14 months later, I was offered my same job back at six months on, six off. I couldn't pass it up. I didn't have quite enough month set aside to ER permanently, but it was close. So I needed some sort of way to set more money aside. So I guess you'd say I was happy to go back to work because I had a job share that gave me time off, yet was making decent money, and I needed the money.
But even though the worst of the problem people had left while I was gone (I'm assuming I wasn't the problem!) after three six-month stints, the money wasn't worth my time and stress, so I quit again. My health was so much better when not working, I figured being a little poorer and ERed was better than richer and dead.
Going back wasn't as hard as I thought it would be, probably because my six months on was in the winter, when I don't play outside as much, and I knew that six months off was coming.
Quitting my job to travel worked out extremely well for me, but I was also fortunate that the market was going up the entire time I was gone (and I traveled cheaply) so I had more money when I came back from my trip than when I left!
Did it convince me that ER was the way to go? Oh yes yes yesssss.