Why do you think I've been inactive lately. Its like a TV show that gets boring over the years, you stop watching but have a little peek in now and then in hopes that it will spark your interest again.
You know what I was exactly like that until not to long ago, what happened was that one day not to long ago I was sitting in a group work shop I had to do for my Personal Training Career and we had to get up and do a group activity where team work was absolutely required, and within a minute or two something click in my head, and for some reason I stop caring what others thought of me and started being myself, and that day potentially changed my life forever.
What I am saying is maybe you should start putting yourself into situations where you have no choice but loosen up. For Example ask a family member or something to throw you in the deep end and sign you up for one of those well being camps where you go away with a bunch of people you don't know for a week or two, or maybe even sign up for a team sport or something. Just keep throwing yourself in the deep end and maybe you'll learn to swim. You may hate it at first, but if it works its worth it right?