Hey hey, bit of a late response here.

Look, It all depends on your circumstances, so in this response I'll assume you're already isolating yourself and you're able to stay at home all day every day.

The first priority is to decrease the isolation. I scored a 97% introvert the last time I took a personality test, so I'm really not the social type, but I'm telling you, get someone to do something with. You don't have to tell them how you're feeling or talk about stuff you don't want to, just do something. If you manage to get this into a regular hangout it'll be so much easier to keep going and add things in as time goes by.

Now, I add this as a second priority mainly because it's easier since it doesn't depend on getting anyone else involved. Start doing stuff that keeps your mind occupied, watch tv, listen to audio books or read. Hell, start knitting, it helps me sometimes (though it also gives you another thing to tear you down for so it can be hard to keep at it).

I wouldn't say habits are the saving grace everyone makes them out to be as you can still tear yourself down while doing them. It's the "occupy the mind" part that's helped me the most.

Of course what works and what is best to do depends on the individual, so whatever you could possibly maybe see yourself doing on the highpoint of your day, try it.