https://www.youtube.com/watch?v=RxPYT-qVyFg
Set a long term personal goal, create a plan to achieve the goal, and execute the plan. Discipline, delayed gratification, and cognitive ability need to be trained just like muscles (see every educational/athletic training program that works, ever).
Folks seem to like Couch to 5k:
If you go that route then a social network wouldn't be there to pick up your feet and move them, and would you really want them to take your achievement away?
If your social isolation is really that bad at "this age" then you might consider if there are any parallels between your situation and people who grew up in, and then left a church like LDS. They often start over from scratch with nothing at a later age.