Brought this over here so I could respond…I agree with Patricia and company…as with many things martial, you imagine a point six inches beyond the target and hit that. Whether you are kicking, head butting or knee striking. Less than that you reduce the effectiveness of the punch…the power disipates as a wave through the body. If you stop, say midway into the target, the energy does not make the full transfer (I don’t remember the physics of it all)…as for form, even going to a Muy Thai gym and watch sparring may give you some help in the right form to use…
Charlie