If you agree to do it, you don't get to complain about it

That's all I have to say.

Edited to add: I do this all the time. Agree to something and then complain, like today - after I agreed to work while on "vacation." And the thing is, I suppose it's okay to complain, sort of (not really), but if you agreed to it, then you can really only thank yourself. I mean, I know how to avoid it, duh, don't agree to do it.