No matter what your fitness goal is I highly suggest you read this article. It goes into excellent detail about why building muscle is important and how to go about doing it. Believe me building muscle is not just for bodybuilders!
Topics in the article include - Why Focus on Muscle? , Why Strength-Training is so effective at burning calories, Muscle Protects your body and mind, Strength training has the hormonal advantage, Foods for building muscle, and so much more.