How much is too much?

Hello everyone. I have had my fibro diagnosis for a little over a year but have largely been in denial. Now I am pretty much over that and trying to figure out how to live with this. Do others experience a really bad day after a good day. My fibro seems to be increasingly more symptomatic and there are days when I can't get much at all done but then I have a day where I feel pretty good and get a lot done. But then the next day I pay for the good day in pain, fatigue and generally feeling lousy. I hate this up and down. How do you pace yourself to not have such extremes?