Qi Gong is unquestionably the best overall exercise you can do to improve your overall health, well-being and happiness because of the impact it has on so many of your physical and mental systems. It is unique in that it is the only exercise that seamlessly combines visualization, stretching, slow movement, meditation, conscious focused synchronized deep breathing, strength building, relaxation, and stress reduction. It requires no special equipment or expensive membership.
Your routines can be done almost anywhere (ideally, outside in fresh air with your bare feet contacting the earth) in just a few minutes a day. You can begin at almost any level of present health and realize noticeable results. It is great when you are young and is one of the very few exercises that can be continued safely for profound benefits into very old age.
Unlike most Western exercises, you feel refreshed and invigorated after a routine, instead of tired and exhausted.
To learn more, a great start is "QiGong for Beginners" by GAIAM. It is a 2 disc set. 1 disc is routines and 2nd disc is PBS TV documentary on "QiGong, Ancient Chinese Healing for the 21st Century" by Gaiam details some of the almost unbelievable results being obtained, and now being scientifically validated, from these simple exercises. Get it from your library or Amazon.
Also see the book, "The Healing Art of Qi Gong: Ancient Wisdom from a Modern Master", by Hong Liu & Paus Perry.