just staying positive isn't enough. You need a reason to keep that positivity up. The best way to do that is to find something you are passionate about. which obviously is hard to do, but still.. I found something that helped me when i was 25. I wasn't passionate about it but I found it so much fun that it helped me a lot. I started travelling alot, especially going to anime cons even though i didn't like anime that much. I did love cartoons as a kid though, as well as the fact that I liked drawing and that was enough of an excuse. So fortunately I lived close by to lots of these things and just kept going to them. The fact that I was travelling, road trips, having adventures, etc. That was making my life so much more interesting. I always went alone of course, I didn't have friends. So because I was exposing myself to people in a social environment all the time, it was easier to follow the other standard advice people give you. You know, like practicing talking to people, keeping positive, having something to talk about (something interesting always happened at cons and that gave me stuff to say at work). The more I put myself in those situations the more I wanted to be one of the normal people out there having fun. So soon it got to the point where I forced myself to talk to a girl because I just wanted so badly to be a normal guy. That was such a defining moment that it snowballed from there that I'd try harder, and it became exciting.
Now I'm not saying you should do this but something along those lines. Find some kind of distraction that really makes you happy and makes your life interesting too. The more you are out there the easier it gets and the more you feel confident about talking to people because you actually have stuff to talk about. Obviously don't go overboard and only talk about yourself but you know what i mean.
As you are doing this, just keep in mind the most important thing is that it's the journey, not any end goal, that is the fun part. The experiences you are getting is what you are after. This really goes a long way in keeping that positive feeling. After a while you will forget about your troubles and then it will happen.. suddenly you will end up with more friends, a girl, and a happier life.. and you didn't do anything crazy to get there, you just tried your best to have fun.