Most people that come to qigong or taichi classes are interested in their health. They are conscious about health aspects and care for a good lifestyle. Usually the reason why they are interested comes from problems they already have. Aching joints, aching back, or stress are common themes. Such persons can certainly benefit from a qigong or taichi practice. That is easy to understand.
What not so many people understand is that qigong and taichi are key practices for prevention. One of my teachers used to say: “the reason why we train today is so that we feel the same in 10 years”. Picture yourself in 10 years. Depending on how positive or negative you are, you'll see yourself 10 years wiser with lots of energy and a strong body, or like a wreck. Certainly, 10 years can change a person dramatically. I believe in what my teacher said. I believe that with regular practice I will see myself strong and healthy in 10 years from now, and another 10, and another 10...
Although the prevention argument is one that is hard to deny, still it is not enough to set most people into action. Most of us are not that smart. That's the human nature: “those things happen to others”. I include myself in there too. The hardest periods in my life have been the catalyst to intensify my qigong and taichi practice.
Since I don't trust myself to be so smart to motivate myself to train so that I can prevent future ailments, and I don't want to wait until having them, I have to find another way to fool myself into training. For me, that is the desire to understand deeper, to take my experience to the next level, to fine tune my inner feelings, and to further my ability. That requires that you have a love for the art, that you do it because you find it interesting and fulfilling, not just as a pill against sickness.
For most people, forcing themselves to join a qigong or taichi class is the perfect excuse to allocate a time slot in their already saturated schedules. Whatever it is for you, find your excuse and fool yourself into training today. Who knows? In 10 years from now you might be smiling at that picture you took today.