I've been going into an office once a week, and I've made more an effort to reach out to friends and try and schedule time to hang out. I've also gone to coffee shops once or twice a week to just work for an hour or two and allow my brain to be distracted by people watching and conversations around me. It's making a big difference in my mental health.
I am terribly shy, so volunteering with strangers sounds terrifying to me. :)