My old job was in a large bank, paid well and i only had to work 4 days a week. The only issue is i wasn't following my passion and it made me feel well and truly down EVERY SINGLE DAY (was there for about 2 years).
For about 3 months prior to putting in my resignation i was also already working on a side project that started getting legs and had started to bring in ramen profitable google ads profit so that It allowed me to quit work and still be able to eat whilst not touching to much of savings along with also paying for some small amazon servers to keep the service running. I thought what the hey, lets give it a go so i quit. Shocked everyone, including parents but i just couldn't go on any longer. It hurt to much... and IT in banks just totally suck.
Also like the article says planned an exercise regime, my work hours for my currently little side project and hanging to start on Peter Norvig and Andrew Ng's classes when they start. Never felt this excited in a while.
I think the caveat though is that while being unemployed (currently like I am) is better then having a lousy job , not being able to put food on the table is lousier then a lousy job. I guess this article applies to people who aren't financially struggling cause i know some people who would take ANY job that came their way right now.