“There’s a moment in fighting when (you realize) the enemy has already given you enough energy to gain the victory.” 
— Toba Beta

To the best of my ability I present a recent lesson from my Tai Chi class:

Teacher: As your opponent moves in, accept their energy as though it were your own.  As you physically drop inward, energetically expand outward and gather all the information you need about the physical event.  This takes a fraction of a second and is before thought.

When you move outward to throw a punch, keep your awareness on dropping inward.  If you focus on the physical action of hitting, you create a double weight and weaken your impact.  Actions are most effective when we don’t try to accomplish them, but hold awareness of their opposite.  If you are sitting, hold the energy of standing.  If you are walking, hold the energy of being still.  If you are punching, hold the energy of dropping.

In this way you let your arm be a limp instrument, energy flows through on its own, you don’t need to add more.

(has me hold pad, knocks me on ground with punch)

Me:  Ow.

Teacher:  It is a continuous surrender, you are always receiving, never doing.

Imagine as though you were falling, notice how tense your body becomes waiting for impact.  Now be aware, if you can relax your reflex to tense, there is no impact.  Everything flows through.  You are constantly surrendering to energy, the idea that there’s something solid that can hurt you will cause you to tense and creates the experience of being hurt.

When you can take in another’s intention fully (be it to help you or kill you) and make it your own, you then have power to respond instantly to the situation without anxiety or fear.

(holds pad for me to punch, there is a light tapping sound)

Teacher:  Let go of the thought that you are going to hit me.  Focus on sensing my presence and energy, let that guide you.  You can respond an infinite number of ways to any circumstance, if you get caught up in knowing what you’re going to do you block yourself.

(I punch again, there is a satisfying whap; my self-esteem soars)

Teacher:  Better.

(bolstered, I envision punching him and knocking him down the way he did me; the next punch is weaker than the first)
Teacher:  Remember, keep your focus internal and do not try for an effect.  You are constantly taking things in, anything else and you block yourself.

Me:  That seems impossible.  How can I be effective if I’m not trying to do something?

Teacher:  It seems impossible to the rational mind.  This isn’t about what you can think of, it’s about what you can perceive when you are still.

(I punch again, it feels like nothing, he is knocked back slightly)

Me:  It’s weird how that works.