I've come up with things I can do with my son that don't involve me getting off the sofa. First I get done everything that needs doing to the best of my knackered ability, then I bring snacks and drinks (so he won't ask me to get him anything) to the couch and we watch a film, or read a book, or I ask him to bring me toys and we look at them together, or we have pencils and paper and I ask him what he wants me to draw and I ask him to draw me certain things (keeps him occupied longer than just drawing whatever). Also, have a bath with your kids if possible - you're going to have a bath or shower yourself anyway, you might as well turn it into some pretty lazy playtime (and save your back from washing them while kneeling on the floor). And while I'm cooking whatever lazy short-cut thing I've decided, I sit him up on the counter and he "helps". These are all ways I stop myself from feeling guilty about not spending quality time with him, without me having to do anything I don't usually do anyway, or without having to move much! Because the exhaustion is real right now.
I work from home, usually while he's at school (he only goes for half a day) but lately I've had to use those three hours to nap because I am soooo tired, which means getting my work done in the morning while he's here. I do feel bad about it, but I do my best as above, and they will never remember this.