First, forget high school. You know what we mean. College is a whole new ball game. Subjects you hated senior year might turn out to be completely different in a brand-new time and place. Mind-numbingly boring civics might suddenly come alive; tear-your-hair-out calculus might suddenly become crystal clear and beautifully illustrated by the physical world around you. In other words, don't automatically rule anything out, even if you don't think it's for you. Give everything at least a small chance. You never know.
Now that you're open minded, take advantage of some of the general education courses you're required to take. Don't just pick whatever's easiest. If your college offers several courses that will fit the requirements, try to choose ones that strike an inner chord, even if they also sound more challenging. "Football Physics" might get you an easy A, but it probably won't make your pulse race or leave you with a real sense of achievement.
And once you're in your classes, be aware of what really compels you. Did the lecture in calculus on Enlightenment philosophers have you on the edge of your seat? Did your ears perk up when your bio professor mentioned the debated origins of life? Have your radar on for clues that might be pointing you in new directions.
Bear in mind, however, that "testing" a major by taking a course in that field sometimes isn't the best way of investigating a major. Courses within a major often focus on a specific topic, and if you happen to find that one topic uninspiring, you might rule out the entire field prematurely. Look for introductory courses that are broad enough to paint a clear picture of what the major is like. Some colleges offer survey courses for just this reason. Or talk to...