Babysteps. I try to get one thing done every day. That's it. Just one. even if it's a really small thing - like taking out the trash or loading the dishwasher or grocery shopping.
And I don't berate myself for feeling down. I allow myself to feel depressed and sad and I treat myself with the gentleness and kindness I would treat another human being with, if I knew they were suffering.
I tell myself this too will pass. And I believe it.
I focus on the present. Not yesterday. Not tomorrow. And if I start worrying about things I cannot control I stop and PURPOSEFULLY change my thinking to something I can control.
I also use a sleep aid - like ambien - when necessary. a goodnights sleep is very important to my sanity and ability to cope.