The "inner strength" of Taiji Chuan is that the body and limbs are obedient when moving. Specifically, under the command of consciousness, any point on the body moves to any position in space, and when there is a little resistance, it immediately stops moving forward and runs in a new direction in a controlled way.
Tai Ji Chuan's "pushing, sliding, squeezing, pressing, picking, bending, leaning, exerting strength and exerting energy" are all manifestations of "inner strength". In short, according to one's own physique and boxing, proceed from reality and take it slowly, which is comfortable and natural. Generally speaking, it is just right to start breathing, stop breathing, open breathing, close breathing and coordinate actions.