Understand the things that you enjoy and try completing them alone. Try doing things that you have never done before in order to build up your interests. If you are an extrovert you may have difficulty with this because you desire to be around people, especially when engaging in your interests. However, the more you practice engaging in your interests alone, the easier it will be.
Keep busy. There are so many options for activities to explore including: art, dancing, writing, reading, playing an instrument, hiking, camping, taking care of a pet, traveling, and cooking. Use a planner to keep track of what you have going on for the week and schedule something in if there is too much empty time. Attempt activities while alone that make you feel social. The extrovert may like to engage in activities that resemble being social while being alone such as texting, chatting on the phone, or going on social networking sites. This can help you feel happier and more socially connected when alone.