Alright whenever doin a box squat your suppose to expand your stomach and push out on the belt if your using one. When you get on the box, do you keep that same breath in or you taking another one and go up? Because holding that breath in the whole way through the excersise kind of leaves me light headed.
DO NOT exhale in the bottom of the box squat. You will lose your tightness, and in my case, buckle the spine. Bad, very very bad.
After you get set take a breath in stay tight, squat down, pause, come back. It should only take you a second or two for each rep, you shouldn't be getting light headed unless you are holding it much longer than needed.