Most people are afraid to be by themselves. That is so dumb. So much in life is better found out by yourself. We end up taking on the emotions of the environment around us. I love to take long walks or even little one day vacations solo. It helps me to recharge my batteries and feel more in tune with my feelings. If you don't feel comfortable doing activities by yourself, start with small doses. Go to a museum or go out to a movie by yourself. I promise that break in interaction with people will do you some good. I am working on this slowly but surely but my goal is take a long vacation by myself and see how much fun I would have! I'm thinking DC or NYC this summer!
Update: I found this article on Thought Catalog while procrastinating - 10 Ways to Have Fun By Yourself. Enjoy!