Um, yes, something always gets dropped. Always.
Ironically, I, one of the more regular exercisers here, dropped exercising off for this last month due to health issues and I still had to drop housework on top of that because of other circumstances!!!
So my approach (and this may not be the wisest), but I mark two goals each day as the 'must-have' goals: one is the must-have for my happiness (exercise is usually this. Sometimes sewing. Sometimes a nap); the second is the must be done for the happiness of the family (usually this is dinner. If I luck out and there are enough leftovers, then it becomes another chore. Sometimes it is doing an art project with the kids and then we have cereal for dinner or smthg equally easy and silly.)
In other words, our household is always running a bit behind somewhere and I have come to terms that this just happens when you have small children. I think our memories of our parents households having it together have a lot to do with us being teenagers helping out with the chores!!!
I think that this season of our lives is more about training than anything else. We are training ourselves to be disciplined and training our children (not just in character, but in helping out around the house). And I think this means that things get done less as a result now for the purpose of being taken care of in the future, if that makes sense.
I'm not saying that I don't get annoyed with the seemingly continual chaos, messes and lack of accomplishments, but I realize that what is more important is my attitude than anything else. And, that brings me back to the main reason I exercise: my mental health.