Although the definition does not explicitly mention "Qi", it emphasizes the mind. When the mind moves, Qi moves; Qi follows the mind, so Qi is naturally included. Would it be better to directly talk about Qi? Not necessarily, because some schools do not practice with Qi. Many Buddhist schools, for example, do not work with Qi. Even Qi-focused practices, at their advanced stages, transcend the focus on Qi.
Using "Qi" to define Qigong would actually narrow its scope. By not focusing on Qi and instead emphasizing the mind, we grasp the very foundation of Qigong. In traditional Qigong, regardless of the school—Daoist, Buddhist, Medical, Confucian, or Martial—as long as it involves genuine practice, it emphasizes using the mind. It's often said, "Success depends entirely on effort applied with the mind." It's all about training the mind. This holds true for Chinese Qigong, and foreign practices also fit this definition.
For instance, Western relaxation therapy requires one to relax; this act of relaxing is about integrating the mind with one's own life activities—isn't that also inwardly directing one's consciousness? There's also a Western psychotherapeutic method where a cancer patient in the U.S. used mental imagery, visualizing their white blood cells devouring the cancer cells, and was cured. This, too, is inwardly directed mental activity, which is essentially practicing Qigong.
(Selected from The Overview of Zhineng Qigong Science and the Lectures by Pang Ming)