Zhan Zhuang Jinggong or Qigong Standing Meditation Postures are a set of meditational rooting postures. Long-term practitioners enjoy benefits, such as the ability to draw “earthly energy” for healing and self-defence, higher bone density, strength in the lower torso, focused concentration and a calm mind, and postural alignment and increased skeletal strength.
Standing Qigong works best as a complementary exercise to Rooting Qigong. Each reinforces the other: they may be practiced together or in separate sittings.
Although these postures are relatively easy to learn, they take time to master. The more relaxed you are, the more body weight is placed on your legs. It takes time for your legs to grow accustomed and build strength and endurance through this exercise.
My advice to you is be patient and persistent. With continued practice you can attain your goal.