the body. you must practice until the mind is calm and then it will be able to imagine.
to test your ability to beam it is necessary to use a simple and often over looked trick. set up a candle and face it, punch, and stop your fist an inch from the flame. do not trick flick the flame by leaving the line of the beam, but focus, and keep the line of the beam as straight as possible.
over time, and as you succeed, stop your fist two inches from the flame, then three. build up distance until you can punch it from across the room and put out the flame. 