Go to the grocery store and ask the Deli crew what they recommend and ask the stockers in Produce about which fruit is in season and tell the baggers to have a nice day and happy holiday season. Making others feel good will make you feel good. Get outside and stay outside more. Walk as much as possible and smile and nod when someone walks by. Put on a good tune and sing while you walk and laugh if someone sees you making a fool of yourself. If you are inside, spend a few minutes answering questions social media or write a nice genuine comment if you read something you liked or someone created something online that made you smile or that you appreciated.
To avoid social isolation, be more social. I am no stranger to living in my own bubble, so no sarcasm intended.
And have a Merry Christmas.