It's a trick my mother taught me. You "steal" resources from one area of your life in order to fill a gap in another. Colloquially, it's called "robbing Peter to pay Paul." Not wise to apply it to finances, but certainly very useful when it comes to domestic life.
For my mother --a single mother with a demanding full-time job and some severely limiting physical disabilities-- "robbing Peter" meant that on a weekly rotation she consciously neglected one area of her life: job, house or kid. Obviously her "neglect" of any of these responsibilities was a matter of degree. She still had work that needed to get done; somebody had to do laundry and grocery shop; and she was always a caring mother.
Basically, my mother accepted the fact that she couldn't give 100% to everything all the time.
It's an example of "realistic mummying" that I did not fully comprehend until I, myself, became a mummy. Now, I try to keep my mother's practical approach in mind, like when we choose goofing off as a family instead of crossing jobs off the to-do list, or not going bike riding for once so I can finally vacuum up the heaps of pet fur.
And I try to cut myself a bit of slack about these choices and to feel okay about being a bit less than universally optimal (like when I completely forgot about not one, not two, but THREE appointments this week!). I guess somedays that's easier than others. :)