How did you/do you afford to be a SAHM?

I'm already mostly a SAHM but I work 8-12 hours per week still. My only baby sitters (in laws) keep going on vacation and I have to keep changing my work schedule around or taking weeks off, etc, and it's just so embarrassing. I would so much prefer to just quit my job so I could focus on my family and not have to inconvenience anyone.

So tell me your story -- what did you do or change or happen to already have that helped you afford to be a full time SAHM?