I've written a bit about lightness before, but "lightness" seems to be a potent trigger word that creates great emotionally charged discussion all over the 'net. Everyone seems to agree it is a Good Thing (TM) but no one can explain exactly what is meant or how to achieve it.
So this short post covers a simple, specific exercise I've found useful to convey the tactile sense of what I'm getting at. I adapted it from some exercises given to me over the years. I've been practicing it again lately.
Take an empty plastic juice-jug, & put 1 liter of water in it. Thread a strap through the handle and put both ends over the back of a chair. Now stand on the other side of the chair and pull up until the jug lifts off the floor.
That is how much contact I keep. Okay, it's the amount of contact I try to keep at all paces and under all conditions.
The second part of the exercise is understanding that while at the trot, the hands stay pretty still, because the horse's heads do not move much, but at the walk and canter, they must move to follow the horse's head movement, so I liken the motion to opening and shutting a drawer. With the jug over the back of the chair, I keep my elbows by my side and just let my hands slide forwards and backwards, as if following the horse's head.
The British Pony club -- I am told -- used to teach exercises such as carrying a tray or cups full of water to teach steady hands. I haven't tried those, although I might remember to bring a couple of coffee mugs to the barn one day.
Please, don't even bother trying to critique this unless it begins with "I tried your exercise..." otherwise, thank you and don't forget to wash your hands.