Think about how much free time you can devote to a hobby or something you would enjoy doing. Some hobbies, such as scrapbooks and gardening, can be rather time consuming. Other hobbies, such as video games or reading, can be done at your own personal pace and do not require any extensive time commitment.
Research the hobby or activity you would like to get involved in. Find out how much time and money you will need to devote to starting and maintaining the activity. For example, some sports-related interests might require special equipment, depending on how involved you decide to become. You can find information about a multitude of hobbies and interests at Find My Hobby's website. This is a directory of hobbies and websites to help you find information and decide if a particular hobby would be right for you. Your local YMCA, library or phone book should also have information on hobbies and activities in your area.
Talk to other people who are involved in some of the activities you are interested in. You can get firsthand knowledge about what you would like to do by interviewing someone about a particular hobby or activity. Ask if you could tag along to a meeting or spend some time with this person while he is involved in his hobby to see if it is something you would enjoy.
Take a chance on an interest and see how things pan out. Challenge yourself to try a new activity you are interested in for a week or so. Allow yourself to learn about the hobby and give yourself time to determine if you will enjoy the activity or not.