I switched from 35-40 hours a week to about 30 hours a week. I found full time work was just interfering with my life and happiness too much. I have a much better balance now. Since I'm young and well paid, it doesn't affect my FI date too greatly. Roughly, it's the difference between being FI between 43-45 and between 47-49. I'll be able to retire early either way. And I just don't know for sure how long my life will be, so I want to make sure I'm fully enjoying the present and not just obsessed with the future.
I'm half of a DINK couple, and my husband is taking the opposite approach - more work now, full retirement sooner. It has a lot to do with our jobs. Mine is easier to do part time. His is very demanding and unhealthy, so the sooner he's done the better.