Ritual, purpose and community are what's required to build a group.

I cured my own loneliness episode by joining a local running group. It provides the same kind of thing as church. Ritual, we meet every week and there's a few different groups. Purpose, it doesn't feel useless to be improving your fitness level. And community comes when you suffer through a run with others.

Showing up regularly means you start to integrate people into your lives as you know when they skip a week for a vacation or something.

I went from living in my town and not knowing anyone for 17 years to having 20+ friends or people I can say hello to and have a chat.

Just find a local running group, or start one. You want the "meet at Starbucks at 6:30 on Tuesday" ones. Show up and keep showing up and you'll make friends. It's impossible to be on your phone when you run and there's always something running related to keep the conversation going.