Visualise strings attached to your head, wrists, knees and feet.
For the moment, be concerned with the head and the wrists... think of being suspended from these points.
Let everything else drape.
Relax the sternum. The lower back. The hip kwa. The back of the knees.
When performing your taijiquan - solo or partnered - maintain this idea of being suspended by strings.
Your arms must feel to float.
Do not confuse this with unfocussed, random movement.
Adhere strictly to the framework requirements, but sustain the buoyant, heavy feeling in the elbows, shoulders, chest and legs.