RIDING THE BALANCED SEAT

WHY DO IT?
If you want to make your Coach happy--TRY TO DO IT!  If you want to have a 'happy' horse--ASK IT TO TRY TO ACHIEVE IT!
The balanced seat is the beginning of mounted co-operation between the Horse and the Rider.
Think about this: the Horse can shiver a fly or bug off its coat/skin; how sensitive is that?  Yet some people seem proud of "de-sensitizing"  their Horse!  Why would any animal or human want to be entered into "dead" actions?   (Futz on that I say!)
Oh, I think I understand what they mean to imply but training a Horse to trust the human's judgement in a frightening situation is not the same as sensitive responses to the Rider's requests.
The goal of keeping the Horse sensitive to the Rider's requests, to form the two into a co-active unit with the least amount of spent energy, should be a major goal.  The Rider should always be aware of the Horse's natural instinct to flee from fearful encounters.
A Rider should not want to 'make' a Horse "light"; a Rider should want to NOT interfere in the Horse's natural Lightness!
A balanced seat produces a balanced load for the Horse to carry.  The Horse learns to trust that the Rider will not unbalance its carriage or its ground-concussion, thereby gaining the freedom to go forward in a regulated and cadenced manner.
CONCLUSION ONE:  the Horse cannot become athletically balanced until the Rider is athletically balanced--and--vice versus.
So, it follows that while a Horse is being schooled to respond to aids and cues and to physically develop its rate, stride, suspension and suppleness, the Rider should also be developing his/her skills--on a TRAINED Horse. (The trained, schooler Horse is the Coach's best friend, these wonderful animals have learned to EXCUSE the struggling Rider and just continue along their way, trusting the Coach!). 
Thus the old saying:  "green Horse/green Rider= failure" proves to be true.
CONCLUSION TWO:  the Horse and the Rider must be capable of mounted work BEFORE being put to it together.  This conclusion demands both physical and mental training and conditioning.  This is why the art of Horsemastery (willing co-operation) takes time and consistency.

Next point:  about degree of training:  most Riders just pile onto the saddle (which may or maynot fit and/or be placed in the proper position upon the Horse) then they bounce about until they land in a heap of some stability, whereupon the Horse learns to balance them and carry their bunden,as they are best able.
Over time the Rider and the Horse find an agreed-to balance between themselves.
THIS DOES NOT MEAN THEY HAVE REACHED THE BEST BALANCE POSSIBLE.
AND IT DOES NOT MEAN THAT THEY WILL ADVANCE BEYOND THIS ACHIEVED LEVEL.

However:  all Riders do not seek discipline beyond basic levels of contentment!  In other words:  not everyone wants to be a trained member of the Ballet.  Many are content to Dance for joy and pleasure (immediate expression)!
For those Riders who want more training, precise timing and mental/physical ability--they must understand technique and must train their muscles/nerves and must include patience in their disciplines.
Think of the hours a skater spends learning to glide without effort, learning to leap at the just-right moment, trusting her partner to do his best when she is thrown out over the ice...just pause and see that mentally.  Hours and hours, why does she do it?  (and him too, why does he?) And those Olympians have Coaches, very able, highly disciplined Coaches.
Move over (mentally) to the Dressage performance pair or to the horse/rider combo approaching the jump or to the rider setting up for reining patterns demonstrations.  The same long hours in the saddle were spent, the same disciplines of muscle/mental controls were established...all...for the love of the work!  All for the love of the goal and the possibility of the achievement. 
And--if the competition is medium to upper levels--they PROBABLY had an educated Coach to lead them to this point!
They probably did NOT teach themselves or train their Horses alone.
So.
As we go forward in these "Lessons"  set your goals firmly in your mind; take no more discipline than you desire, NEVER lose your pleasure in being with the Horse; and remember that your goals (dreams) can prove to be beyond your talents or your horse's talents, so acceptance of the highest level of achievement must always be the ULTIMATE goal!
If you 'want it' and your horse 'likes it' then you can try to 'do it'.  If you can't reach the goal, after you have accepted the work and discipline and talent involved; perhaps you should find happiness with the highest level actually achieved.
PLEASE...do not blame your Horse...or quit too soon and blame yourself !  I have seen instances where adjusting the placement of the saddle or developing a specific exercise has made the difference in the solution to a problem.
There is NEVER a moment, in training, for anger or cruelty or overt force--if the Rider cannot Love the Horse's condition then s/he SHOULD not be engaged in this Art!
Remember:  'going for the gold' can bring on tears and frustrations and sadnesses as well as successes. 
This blending of the Horse and Rider into a partnership has its challenges.  But this goal is ALWAYS correct to people who just plain love horses!  Coach