It will depend on what you like to do and be engaged with the most. For example, if you like hiking is a good option because there use to be be lots of groups everywhere.
If you like animals you can offer a hand there and meet like-minded people.
The same with other activities as drama groups, dancing learning, or any kind of learning -a new language-, etc. It will all depend on your likes, your level of energy, the time you have available taking to account the hours you have to dedicate to your job.

P.S.: I know it’s not easy when you feel a low mood. At least, I hope you don’t have social anxiety. I don’t know it. In this case, it would be even more difficult.