What helped me the most was reading the book "How to Win Friends and Influence People" and following the instructions. It's cheesy, it's old school, it's a classic, it's outdated but darn it the (outdated) advice in that book really does work, and it really did help me turn my personality around and even improved my outlook on life/humanity. I didn't really take an interest in others that much beforehand, but once I started being more extroverted and chatting with others, more people became my friend and I feel more engrossed in my community- I even know my bank teller and sandwich guys names now and realized I'm downright cheerful at times. I take more of an interest in others and keep getting promoted at work due to what seems solely on my personality... I mean, my quality of work is good, too. For example, a recent award I won cited, "your positive energy is contagious and especially welcome tackling tough projects."

But yeah... that book brought me from a depressed cynic to someone who takes an interest in others and basically the whole world is my friend- even people I haven't met yet, they are just friends I don't know yet.