Find the books from Dorrance and Ray Hunt or if you want to go 19th century "old school" look up professor beery. Hunt/Dorrance improved those methods.
"natural horsemanship" isn't new or the flavor of the week, we used the same methods 35 years ago in California.
Its what the above posts say, seems when the horse went from everyday companion and necisarry for life, the car/truck/tractor ended this. Most people here still do it the way you see in the old westerns where you:
1: snub the 2 year old up, put saddle on and blindfold
2: dumb cowboy climbs on and holds on for dear life and waits for bucking to stop.
3: further training requires a stick to the head
4: problem arises see step 3
And a lot of other arcane methods to literally break the horse's spirit
Experience has taught us that work them in the round pen, expose them to everything on the ground.... build up the horse's trust then confidence then communicate what you want them to do.... and wet blankets the more sweat equity invested the better your horse is.
Also the round pen does not equal lungeing for 15 minutes.... all that gets you is a horse that's in shape and still has a bad habit