I did this in 2013. Went from working in a lucrative, stressful high frequency trading systems development environment, into developing systems for humanitarian organizations. Loved the work, the next two years were the happiest and the most chilled out in my life. The negatives: burnt through a lot of my savings. I'm back in a different industry now, and the return was a bit painful, but looking back, it was one of the best decisions I've ever made.
Advice:
1. Have at least two years worth of savings, or an alternative source of income that can cover all your basic expenses, or don't do it.
2. Don't take a job that requires you to work harder than you did in your old job. In the beginning, the change will be invigorating, but soon it'll start to wear you down. During my "sabbatical", I worked only six hours a day at most, saving plenty of time for family and personal pursuits.
Advice:
1. Have at least two years worth of savings, or an alternative source of income that can cover all your basic expenses, or don't do it.
2. Don't take a job that requires you to work harder than you did in your old job. In the beginning, the change will be invigorating, but soon it'll start to wear you down. During my "sabbatical", I worked only six hours a day at most, saving plenty of time for family and personal pursuits.