Why posing while doing something fake kills your photo

Pretending to walk somewhere or putting on a jacket for the camera does not work. The rule is simple: only do something in a photo if you would naturally be doing it without a camera present. If you are lighting a cigarette or a cigar and you look down to do it, that is genuine. But faking an action just to avoid standing still is obvious and unconvincing. When in doubt, stand in front of the camera, look straight at it, mouth closed, with a slight smile if you like. Simple and direct beats manufactured every time.