I'm successful at my job, but not my social life?

I have my dream job which I am very good at....respected completely at my office, but when I leave I don't have anyone at home. No friends, girlfriend, nothing. I could probably attribute my lack of a social life to working so much, but I'm quite hard on myself and expect to be able to have the same networks I did when I was in college. I know that is ridiculous and I would like to change it, but it is quite daunting.