We have all been asked or will be asked to define intensity as it relates to Kung Fu. There is no simple answer to this and it will be different for all of us. To me intesity is doing something with a purpose. I am not just going through the motions but I have an objective and a set path on how to get there.
There are a few things you can do to try and fake intensity but there is always one tell. The eyes never lie. You must look where you want to go and don't stare at your oppenent but burn a hole through them with your gaze. You have to believe what you are doing and every strike will obliterate whatever is in your path. Have confidenc in your abilities and the intensity will be there.