nightowl, brilliant to read you are working on a dressage test after 20 years out of the saddle. I wish I could ride again but have to accept that this isn't something I'll be able to do.
I've been thinking about the worries people (non riders I think) here have expressed about the impact of dressage on horses. It's reminding me of pilates or probably ballet. Yes, it's tough but if a horse has the temperament and physical ability to do the work, they will love it.
I'm just back from a specialised dog training group with my (difficult) young dog. He loved the challenge and is snoring on his bed right now. He not only enjoyed the work, you could see the pride he felt in his achievements. I know, its a dog, not a horse - but working with an animal you love is just so rewarding.