Economics of changing careers halfway through life?

http://tech.slashdot.org/story/11/12/03/1435217/half-life-of-a-tech-worker-15-years

I'm not even sure if I will be able to make it to 15 years, I have worked full time for the last 8 years, and part time & college for 4 years... Is there a name other than retiring? I would consider becoming an inverter or photographer, or be willing to volunteer with the Red Cross or Engineers Without Borders.

The question I am faced with is what should I do? Where do I go from here?

I have enough money saved to live a minimalist lifestyle that would be more interesting than working, but I might have to sell my current home with the property taxes, insurance, HOA fees, utilities, etc... One option is to live on a sailboat and migrate north and south with the seasons. It would be nice to be in the Bahamas today instead of Ohio. The other option is to be a bicycle tourist for a few months. It would be an interesting way to see the world and be more relaxing than my 'vacations' I take now. (crazyguyonabike.com has a bunch of blogs about it)

The problem economically is, it is too easy to get the bi-weekly paycheck and decent health and dental benefits. I can plan a little bit, yet I am too burned out to do any real investing or the 'typical' retirement account plan (I do have more in a 401k and IRA than half the baby boomers, yet I'm 10-30 years younger than where people retire at normally).

My finances are pretty simple. I don't have a wife, kids, or pets. My hobbies are a little pricy at first, but once you have the gear it is cheap. And I know how to do free things. Unless I somehow could get my invention to market and sell a few thousand while I still have my day job, I'm afraid people would think I am crazy to give up a stable job now.

Have any of you changed careers or changed jobs? I'm not even sure if I would like a different job, but that is a different topic. Should I go watch Office Space, because I feel a lot like the engineers in that movie.