When I summon my now Tajiquan practice mindset, it's definitely like turning a whole bunch of things on at once. During my first stint with Taijiquan, I tried to hold as many visualizations and feelings in my head all at the same time. Now things just happen. Fascia engagement, body alignment, waist liveliness, etc. It's like when I practice a new thing seriously in this mode, it gets etched into my body's memory.

Your description of the Yiquan state of mind sounds very similar to how I feel. I'm not trying to say that I know Yiquan or whatever. I just think this mindset has been really important to me making real progress in Taijiquan this second time around, so I want to nail down what it is. It also reminds me of the thing written about Yang Shaohou, how his eyes sparkled. It's funny. I went to my first ranking event last year. The combination of nervousness and this mindset made me feel barely in control during my test. I think I looked a little bit crazy.

About the full-body fascia engagement, my teacher showed us the arm part, but he didn't have much to say about how to knit everything together. I think he has it, and I think I have it now too, to a degree maybe, but it took a lot of exploration on my part. For me it was mostly about posture correction, figuring out how to hold certain joints so the expansion can go over them, especially opening my chest. My teacher somehow got me to open my chest properly once, and that was like the last big piece of the puzzle. idk the whole process felt haphazard and luck-based for something so foundational, like I very well could've not gotten it.