I find that I am putting everything on hold - "I will do xyz one day in the future when the children are finally sleeping through the night".
I save my (limited) energy as much as I can, and recommend doing one or two housework jobs each day rather than a whole house blitz. That way I feel bizarrely more in some sort of control over it all, rather than overwhelmed all the time. Better still pay someone to do it for you!
I don't iron anymore, except if I go to a party or a wedding. I bought a robot hoover when my last one died, best purchase from Amazon ever 
I also do far more online shopping than I ever used to, for an easy life and to be kind to my poor tired body!
I sleep as much as I can when the baby does. I climb into my 3 year old's single bed for a cuddle until he's back to sleep when he wakes up having nightmares. It makes nights easier because no sooner have I returned to bed, he will start up again. Saves the up/down all night nonsense which is exhausting! He's rarely slept a whole night since being born and I'm thinking any day now we'll get lucky.
I do as much as I can to be organised which helps conserve energy, even if its only thinking power. Someone once said "a job done at night it 3 times faster than a job left til the morning." That's true for me and so I apply it to getting the table laid up (the night before) for breakfast and preschool bag sorted etc.
I really really wanted this little second baby, and for a long time we thought we'd never be able to have a second child, so in the dark of night I remind myself how much of a gift he is, and how that one day this awful torturous sleep deprivation will be a distant memory.
Meanwhile I am we all are in survival mode and living as simple a life as possible. For the moment.