Everything in life takes practice.
Sometimes that means refraining from sending inappropriate texts, not going back to our exes, not shop lifting, not using drugs. Once it becomes habit like you said, it is hard to just kick it completely. The bright side to that truth is that with practice, things -do- become easier, and we do get closer to the person we want to be.

I empathize with you being afraid of living alone. I lived alone the past couple of years, and it was very difficult to get myself out of my room... as much as I -liked- the privacy, in a way, it made my condition worse, because I allowed my living conditions to slip without anyone knowing.
Maybe make a point to do something simple, like go get a coffee one day, or even write or draw at the shop if that's something you enjoy. Go to a trivia night, the gym, or a movie, etc. Anything to break you out of the shell a bit.