I'm a little odd. I have a lot of stress over financial insecurity. So for me, its very important that I have a savings account, enough income coming in that my net worth is increasing, and low enough spending that my net worth is increasing. When that isn't happening, there is a whole lot of stress in my life. Stress is not condusive to happiness. Now, those numbers might not need to be large (they have been large, so the stress of paying for kids college is gone, the stress of saving for retirement is gone, the stress of 'if my husband gets laid off we could lose the house' is gone). However, I know this about myself.
I have a girlfriend (several friends actually, but one in particular) who it doesn't bother to be much closer to the edge. She is quitting her job and they are living off her husbands much smaller part time income. When I do the math, my stomach turns knotty, because nothing can go wrong or they will be screwed. But she is comfortable with it, they've taken similar steps before. And she figures that if things go wrong, she'll get a different job, and his job is secure and they'll pay the mortgage and feed the kids, and if everyone is wearing two sweaters in the winter, as long as the heat is high enough so the pipes don't freeze, they'll all survive.