One thing that does help me is to remember the practical assists that the go-getters typically have. Or even that Charlotte Mason had. She could spend hours outside with children every day because someone else was mother, yet another person was cooking/cleaning, etc. SWB's kids are (probably?) grown at this point. When they were younger, her husband helped teach, and iirc, so did her mother. Someone else held down the fort while she was teaching classes. She has a staff at Peace Hill Press, too. If it's all you all the time, there are less obviously productive things you can get done. Here prioritizing helps tremendously to at least mitigate some of the mama guilt. And looking at time with opportunity cost in mind.
And I say "obviously productive" because often something like meal planning, grocery shopping, then cooking, clean up, dishes, plus overseeing mealtime isn't really "counted" in most people's minds as work or productivity. Same thing for keeping the house in order (often in the face of resistance), knowing where everything is in the house at any given time, who needs what and when, and so on. All of that is brain power. Being accessible to demanding little people 24/7 takes energy (especially if you're trying to stay pleasant 24/7!). And then if you are handling finances, household business, side work, side projects, yard work, pets, new skills, volunteer work, faith stuff, etc., that's just that much more, however much more it is (the bigger the house, the more pets, the bigger the yard, etc. all increase the load compared to fewer or smaller).
None of this is to negate the importance of taking care of yourself or powering through certain things, though; just an additional dimension that I think is often overlooked. :)