Have you ever tried the Horse Stance? It is a classic training posture throughout many martial arts. Here he is teaching it in the context of Baiji rather than Taiji (Tai Chi). The name makes more sense as "horse riding stance" since that is what it looks like. It's basically an isometric squat. Wider and lower makes it harder, narrow and high is easier. Longer duration also increases the difficulty. You can even do a wall sit to help with balance. It is typically stationary but moving variations keep you from getting bored with it and give you intervals to play with. Balance and leg strength are major factors when it comes to longevity. ENJOY. 🙏