The 2nd chakra is called "Svadhisthana," which mean's "one's own place." The 2nd chakra is about having fun, connecting to your emotions, going with the flow of life. It also is related to sex in terms of the joy of sex. When in balance, you flow with change, are connected to your emotions, and have fun. Excessive would mean that all you do is have "fun," which after awhile isn't such a good idea. Deficient is that you are closed off from your emotional self, and from the joyful movement and flow of life.
The way to find balance when deficient in the 2nd chakra is through opening and movement in the hips.