It was always explained to me that in Sun Style the mind is the most important thing, 75% is intent in doing the movements and 25% physically performing them, I think this is a very difficult concept to understand unless you break it down in other ways for example, doing the Taiji with 25% effort but 75% concentration.
The most important movement according to teacher Lei Shi Tai is Pi Quan and this should be done slowly and softly but with 100% concentration on every movement. If you feel something different in the movement you should examine it with your mind, adjust it to what it should be and continue. Some days I just did Pi Quan for an hour nothing else! I maintained this routine, just teaching the form and other Xing Yi and so practicing it. The benefits from just doing Pi Quan on the rest of the Sun Style was amazing it improved everything.
This is really cutting down to a base movement no other movements needed just one fist to make all others.