A simple bit of advice, really; let yourself be interested. Not take an interest, but let yourself be interested. Let yourself be intrigued, amazed, thilled, appalled by what you hear around the table. Let yourself become a part of the world that's being presented to you.
Some months back Gerard Vanderleun of American Digest (http://www.americandigest.com) got to thinking about a scene in a movie. A scene where the hero tells the mentor that there's nothing going on. As I recall Gerard's retelling the mentor told the hero, "There aint nothin' going on."
Gerard went on to say that most of us go through life asleep. We don't pay attention to what goes on around us, because we have convinced ourselves it isn't interesting. He then told of a walk he took in which he paid attention to what was going on around him, and found himself engaged with the sights and people he saw and met along the way in a way he never had before. He awoke to the possibilities and by letting himself be interested in his world he had a more interesting time than before.
An RPG is not a passive entertainment, it is an active one. To truly be entertained you need to participate, you have to let yourself be interested. You don't you will not enjoy yourself as fully as you could.
I'll bet a lot of people reading this have elements they are interested in. Combat usually. Why is that? Because they find it interesting? No, because they let themselves be interested in it. Let yourself be interested in other aspects and you may find them just as exciting as combat. You may not, but you can't know until you make the effort.
Let yourself be interested in the word you game in, in the people who live in that world. Let yourself be interested in that world's history, philosophy, and faiths. Let yourself be interested in what is going on in that world. And for you GMs out there, let yourself be interested in the people your group plays. Interested in their stories, their histories, fears, and dreams.
Yes, it means more work. So let yourself be interested in the work, in the process of making a better experience for you and your friends. I think you'll find the results rewarding.