Would I shift my body weight to absorp the energy, or stand like a brick wall using muscles and energy to resist?

Neither. It has to do with connecting your structure and using the ground. Pusher should feel like they are pushing against the ground.

Oh, and you should be somewhat "relaxed". (See Ed's previous post regarding being "relaxed").

I'm reviving this thread because it's good and has a couple of points I would like some extra information on. The first one I can recall involved keeping the abdomen tight and still being able to breathe deep. I have a lot of difficulty with that technique, however, I believe it to be very useful and would like to develop it further. Do you have any info on it besides practicing breathing with my abdomen contracted?

Well, what are you doing when you're doing "normal" breathing and "reverse" breathing?

As far as normal breathing goes, I'm not keeping my abs tight while doing it. I'm not even sure what reverse breathing is about.

OK, imagine your whole body is a balloon - like the Michelin Man. When you breathe in (normal breathing), expand your entire body (like you're filling it with air).

Imagine all the pores in your skin opening up to suck the air into your body. You should feel your abs and thoracic cavity automatically stretch to fill out.

Pause and hold your breath momentarily and engage the "3 locks". This pressurizes the breath in your lower thoracic cavity. Because internal pressure is involved, you want to ease off on creating too much tension or too high a pressure differential, lest you pop a capillary or 2. The idea is to SLOWLY build up the strength of your vascular system. i.e. breathe deeply, but "normally".

On the exhale, contract your abs and deflate your balloon body. You will soon notice that you have some control over your abs - like a bellow. That's why it's called abdominal breathing. Nothing special here - endurance athletes and singers learn to do this.

Reverse is exactly as it says - the opposite of abdominal breathing. Note the change in pressure differential and where in the thoracic cavity.

Obviously there's a lot more to it, (see preceding posts) but that'll keep you going for now.