>>2327603Go outside more often, even just for walks.
If you have a hobby, use the internet to find other people who have that same hobby and try to interact with them.
If you don't have a hobby, find one, or just pick a hobby at random and give it a try.
If you're doing all of these things and are still sad, try to see a doctor about it if you can.
If work and social fulfillment aren't working for you, it's possible you need more professional help.