Pacing Ones Self

I'm sure this applies to a lot of us. I notice how hard it is for me to pace myself throughout the day. Everyone says "don't over do it". I personally still haven't been able to learn what my limits are. Very few days have been good for me.  So when I have a good day, I want to do everything and anything while I feel good. Then I wonder is that what put me back in bed for the next three days? What a vicious cycle this is.