A lovely piece by Leo Babauta of Zen Habits on getting started with a meditation practice and the benefits of doing so:
Lots of people think meditation is about clearing your mind, or stopping all thoughts. It’s not. This can sometimes happen, but it’s not the “goal” of meditation. If you have thoughts, that’s normal. We all do. Our brains are thought factories, and we can’t just shut them down. Instead, just try to practice focusing your attention, and practice some more when your mind wanders.