The essence of Xingyi practice is that you experience 'chambering' on every rep, in any Fist or Animal of the art. So what is that: 'chambering' ? I will explain. But bear in mind the problem that if you haven't cultivated and deployed the internal energy to be pretty significant you won't understand. Not your fault: you cannot understand. It will be literally uninterpretable to you. But save this post because someday if you keep working you'll get it and you'll think back to this.
In a firearm, chambering is positioning a bullet from the magazine into the ready position to fire. It's poised to go. People also use this word in karate and other kicking styles, where they talk about raising the bent leg to an optimal height and configuration before the last stage of firing a kick. All those things however are physical.
Chambering in Xingyi has some conceptual commonality with those 'final prep' types of actions (that's why I've borrowed the term), and yet as a purely energetic process, it's also fundamentally different The simple way to say it is that in every rep of any Xingyi technique, there's at least some kind of intro gesture, usuallly combined with at least a half step, sometimes several gestures and steps. Then you actually "fire" your main strike of the rep.
During the intro steps/gesture, you need to activate your lower platform. It's basically legs, femoral joints and hips. The culmination of that process, which then leads seamlessly into the actual firing of your strike, is a sudden, instantaneous, almost violent (but not painful or injurious) energetic crystallization at your abdomen and pelvis. You probably don't feel that now, and don't start tensing up there just to feel something. It has to be the real energy. It's so powerful that it will feel like a solid thump on your abdomen. It's the moment of the power "hitting and filling" your abdomen and hips, on its way up quick from below, that I call chambering, and it must happen for the subsequent strike to be actual Xinyi (as opposed to "bad karate"). In the beginning my teacher tried to prep me for this using the staff hits on every rep (see illustration of him doing that in my book Infusion). But then I didn't understand the point at all. You can't really, until you have sufficient energy cultivation.
Once you feel that, only then, and tangibly, but not in slow motion, not rushing your technique, just moving at "the speed of life" (natural), then you launch the actual strike. As you begin the upper body final part of the technique, you'll realize one day "Oh - the power has chambered (felt that clearly!) and now for one mico second it's staging from my heart center, in front center chest. Yes it transits there and then instantly fills your arms for the final extension into the strike portion of the technique.
I've written about this in my books and here so I won't go into it further now. But that's the full process. Every step, though quick and connected, is fully tangible and is experience deeply though briefly on every rep. It's super amazing, honestly. But if there's not clay/gas there's not way to experience or appreciate it, and most people will tense up their shoulders, fists, and muscles in the final strike, just in order to feel something at least. That will totally block you. You must be crisp yet relaxed to let the energy surge up and through your body, including head. I'll cover all this in my yearly even this weekend.
Teaching Xingyi to almost anybody regardless of backgroun is like a master potter conducting a pottery class, with the potter's wheels all set up and everybody in a smock and the clay tools laid out - but nobody actually has any clay on their platter there. Or teaching driver's ed in a car with the gas tank completely empty. It's weird.
So cultivation has to come first. Still its good to run through the techniques regularly so that eventually the cultivation and deployment streams will converge.